diff --git a/changelog.html b/changelog.html
index eba0ec5ff2ad5ed88834208c6205127fb0e7046b..aba59531f817d8b1d9f4a4f26d499ebb8a7f3976 100644
--- a/changelog.html
+++ b/changelog.html
@@ -54,6 +54,19 @@ Upcoming changes</a>
 
 <!-- Record your changes in the trunk here. -->
 <div id="trunk" style="display:none"><!--=TRUNK-BEGIN=-->
+<ul class=image>
+  <li class=bug>
+    Fixed <code>NullPointerException</code> caused by the uninitialized <code>ProcessStarter</code> environment in build wrappers
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20559">issue 20559</a>)
+  <li class=rfe>
+    API changes allowing to create nested launchers (<code>DecoratedLauncher</code>)
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19454">issue 19454</a>)
+</ul>
+</div><!--=TRUNK-END=-->
+
+<!-- these changes are controlled by the release process. DO NOT MODIFY -->
+<div id="rc" style="display:none;"><!--=BEGIN=-->
+<h3><a name=v1.567>What's new in 1.567</a> <!--=DATE=--></h3>
 <ul class=image>
   <li class="bug">
     Fixed a reference counting bug in the remoting layer.
@@ -82,6 +95,10 @@ Upcoming changes</a>
   <li class="bug">
     Process the items hierarchy when displaying the Show Poll Thread Count option
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22934">issue 22934</a>)
+  <li class="bug">
+    Compressed output was turned on even before Access Denied errors were shown for disallowed Remote API requests, yielding a confusing error.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17374">issue 17374</a>)
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-18116">issue 18116</a>)
   <li class="bug">
     Properly close input streams in <code>FileParameterValue</code>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22693">issue 22693</a>)      
@@ -113,11 +130,8 @@ Upcoming changes</a>
     Added an option to archive artifacts only when the build is successful
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22699">issue 22699</a>)
 </ul>
-</div><!--=TRUNK-END=-->
-
-<!-- these changes are controlled by the release process. DO NOT MODIFY -->
-<div id="rc" style="display:none;"><!--=BEGIN=-->
-<h3><a name=v1.566>What's new in 1.566</a> <!--=DATE=--></h3>
+</div><!--=END=-->
+<h3><a name=v1.566>What's new in 1.566</a> (2014/06/01)</h3>
 <ul class=image>
   <li class="rfe">
     Configurable case sensitivity mode for user IDs.
@@ -132,7 +146,6 @@ Upcoming changes</a>
     Jenkins cannot restart Windows service
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22685">issue 22685</a>)
 </ul>
-</div><!--=END=-->
 <h3><a name=v1.565>What's new in 1.565</a> (2014/05/26)</h3>
 <ul class=image>
   <li class="bug">
diff --git a/cli/pom.xml b/cli/pom.xml
index 711bcde229e39f711702d3fd6e4000ccc55aa0f2..d9b86906b0c82350b85fc83b723edc77f2675d10 100644
--- a/cli/pom.xml
+++ b/cli/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <artifactId>pom</artifactId>
     <groupId>org.jenkins-ci.main</groupId>
-    <version>1.567-SNAPSHOT</version>
+    <version>1.568-SNAPSHOT</version>
   </parent>
 
   <artifactId>cli</artifactId>
diff --git a/core/pom.xml b/core/pom.xml
index cccf922c7d6bd133f44d83d4e59f9454877e1de8..e9be9512eddc98aea0ff936385f284818041cb1a 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -29,7 +29,7 @@ THE SOFTWARE.
   <parent>
     <groupId>org.jenkins-ci.main</groupId>
     <artifactId>pom</artifactId>
-    <version>1.567-SNAPSHOT</version>
+    <version>1.568-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
diff --git a/core/src/main/java/hudson/Launcher.java b/core/src/main/java/hudson/Launcher.java
index 39d1a56b1371a5a244fe60da47a179eb11c11c95..b08dfaf0f139163abb056326c640c50cfbd839b5 100644
--- a/core/src/main/java/hudson/Launcher.java
+++ b/core/src/main/java/hudson/Launcher.java
@@ -300,8 +300,13 @@ public abstract class Launcher {
             return this;
         }
 
+        /**
+         * Gets a list of environment variables to be set.
+         * Returns an empty array if envs field has not been initialized.
+         * @return If initialized, returns a copy of internal envs array. Otherwise - a new empty array.
+         */
         public String[] envs() {
-            return envs.clone();
+            return envs != null ? envs.clone() : new String[0];
         }
 
         /**
@@ -972,6 +977,88 @@ public abstract class Launcher {
             }
         }
     }
+    
+    /**
+     * A launcher which delegates to a provided inner launcher. 
+     * Allows subclasses to only implement methods they want to override.
+     * Originally, this launcher has been implemented in 
+     * <a href="https://wiki.jenkins-ci.org/display/JENKINS/Custom+Tools+Plugin">
+     * Custom Tools Plugin</a>.
+     * 
+     * @author rcampbell
+     * @author Oleg Nenashev, Synopsys Inc.
+     * @since TODO: define version
+     */
+    public static class DecoratedLauncher extends Launcher {
+
+        private Launcher inner = null;
+
+        public DecoratedLauncher(Launcher inner) {
+            super(inner);
+            this.inner = inner;
+        }
+
+        @Override
+        public Proc launch(ProcStarter starter) throws IOException {
+            return inner.launch(starter);
+        }
+
+        @Override
+        public Channel launchChannel(String[] cmd, OutputStream out,
+                FilePath workDir, Map<String, String> envVars) throws IOException,
+                InterruptedException {
+            return inner.launchChannel(cmd, out, workDir, envVars);
+        }
+
+        @Override
+        public void kill(Map<String, String> modelEnvVars) throws IOException,
+                InterruptedException {
+            inner.kill(modelEnvVars);
+        }
+
+        @Override
+        public boolean isUnix() {
+            return inner.isUnix();
+        }
+
+        @Override
+        public Proc launch(String[] cmd, boolean[] mask, String[] env, InputStream in, OutputStream out, FilePath workDir) throws IOException {
+            return inner.launch(cmd, mask, env, in, out, workDir);
+        }
+
+        @Override
+        public Computer getComputer() {
+            return inner.getComputer();
+        }
+
+        @Override
+        public TaskListener getListener() {
+            return inner.getListener();
+        }
+
+        @Override
+        public String toString() {
+            return super.toString() + "; decorates " + inner.toString();
+        }
+
+        @Override
+        public VirtualChannel getChannel() {
+            return inner.getChannel();
+        }
+
+        @Override
+        public Proc launch(String[] cmd, String[] env, InputStream in, OutputStream out, FilePath workDir) throws IOException {
+            return inner.launch(cmd, env, in, out, workDir); 
+        }
+   
+        /**
+         * Gets nested launcher.
+         * @return Inner launcher
+         */
+        public Launcher getInner() {
+            return inner;
+        }    
+    }
 
     public static class IOTriplet implements Serializable {
         InputStream stdout,stderr;
diff --git a/core/src/main/java/hudson/Util.java b/core/src/main/java/hudson/Util.java
index 2934a79a4f9ec629b4bb267c172187054cc8ef7f..b7725aa68fcba854bb08034d77412e07cee83bd1 100644
--- a/core/src/main/java/hudson/Util.java
+++ b/core/src/main/java/hudson/Util.java
@@ -73,6 +73,9 @@ import hudson.util.jna.Kernel32Utils;
 
 import static hudson.util.jna.GNUCLibrary.LIBC;
 import java.security.DigestInputStream;
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import org.apache.commons.codec.digest.DigestUtils;
 
 /**
@@ -94,7 +97,8 @@ public class Util {
      * Creates a filtered sublist.
      * @since 1.176
      */
-    public static <T> List<T> filter( Iterable<?> base, Class<T> type ) {
+    @Nonnull
+    public static <T> List<T> filter( @Nonnull Iterable<?> base, @Nonnull Class<T> type ) {
         List<T> r = new ArrayList<T>();
         for (Object i : base) {
             if(type.isInstance(i))
@@ -106,7 +110,8 @@ public class Util {
     /**
      * Creates a filtered sublist.
      */
-    public static <T> List<T> filter( List<?> base, Class<T> type ) {
+    @Nonnull
+    public static <T> List<T> filter( @Nonnull List<?> base, @Nonnull Class<T> type ) {
         return filter((Iterable)base,type);
     }
 
@@ -122,7 +127,8 @@ public class Util {
      * Unlike shell, undefined variables are left as-is (this behavior is the same as Ant.)
      *
      */
-    public static String replaceMacro(String s, Map<String,String> properties) {
+    @Nullable
+    public static String replaceMacro( @CheckForNull String s, @Nonnull Map<String,String> properties) {
         return replaceMacro(s,new VariableResolver.ByMap<String>(properties));
     }
     
@@ -132,7 +138,8 @@ public class Util {
      * <p>
      * Unlike shell, undefined variables are left as-is (this behavior is the same as Ant.)
      */
-    public static String replaceMacro(String s, VariableResolver<String> resolver) {
+    @Nullable
+    public static String replaceMacro(@CheckForNull String s, @Nonnull VariableResolver<String> resolver) {
     	if (s == null) {
     		return null;
     	}
@@ -165,11 +172,13 @@ public class Util {
     /**
      * Loads the contents of a file into a string.
      */
-    public static String loadFile(File logfile) throws IOException {
+    @Nonnull
+    public static String loadFile(@Nonnull File logfile) throws IOException {
         return loadFile(logfile, Charset.defaultCharset());
     }
 
-    public static String loadFile(File logfile,Charset charset) throws IOException {
+    @Nonnull
+    public static String loadFile(@Nonnull File logfile, @Nonnull Charset charset) throws IOException {
         if(!logfile.exists())
             return "";
 
@@ -195,7 +204,7 @@ public class Util {
      * @throws IOException
      *      if the operation fails.
      */
-    public static void deleteContentsRecursive(File file) throws IOException {
+    public static void deleteContentsRecursive(@Nonnull File file) throws IOException {
         File[] files = file.listFiles();
         if(files==null)
             return;     // the directory didn't exist in the first place
@@ -208,7 +217,7 @@ public class Util {
      * @param f a file to delete
      * @throws IOException if it exists but could not be successfully deleted
      */
-    public static void deleteFile(File f) throws IOException {
+    public static void deleteFile(@Nonnull File f) throws IOException {
         if (!f.delete()) {
             if(!f.exists())
                 // we are trying to delete a file that no longer exists, so this is not an error
@@ -259,7 +268,7 @@ public class Util {
     /**
      * Makes the given file writable by any means possible.
      */
-    private static void makeWritable(File f) {
+    private static void makeWritable(@Nonnull File f) {
         if (f.setWritable(true)) {
             return;
         }
@@ -287,7 +296,7 @@ public class Util {
 
     }
 
-    public static void deleteRecursive(File dir) throws IOException {
+    public static void deleteRecursive(@Nonnull File dir) throws IOException {
         if(!isSymlink(dir))
             deleteContentsRecursive(dir);
         try {
@@ -321,7 +330,7 @@ public class Util {
      * Checks if the given file represents a symlink.
      */
     //Taken from http://svn.apache.org/viewvc/maven/shared/trunk/file-management/src/main/java/org/apache/maven/shared/model/fileset/util/FileSetManager.java?view=markup
-    public static boolean isSymlink(File file) throws IOException {
+    public static boolean isSymlink(@Nonnull File file) throws IOException {
         Boolean r = isSymlinkJava7(file);
         if (r != null) {
             return r;
@@ -350,7 +359,7 @@ public class Util {
     }
 
     @SuppressWarnings("NP_BOOLEAN_RETURN_NULL")
-    private static Boolean isSymlinkJava7(File file) throws IOException {
+    private static Boolean isSymlinkJava7(@Nonnull File file) throws IOException {
         try {
             Object path = File.class.getMethod("toPath").invoke(file);
             return (Boolean) Class.forName("java.nio.file.Files").getMethod("isSymbolicLink", Class.forName("java.nio.file.Path")).invoke(null, path);
@@ -379,13 +388,14 @@ public class Util {
      * On Windows, error messages for IOException aren't very helpful.
      * This method generates additional user-friendly error message to the listener
      */
-    public static void displayIOException( IOException e, TaskListener listener ) {
+    public static void displayIOException(@Nonnull IOException e, @Nonnull TaskListener listener ) {
         String msg = getWin32ErrorMessage(e);
         if(msg!=null)
             listener.getLogger().println(msg);
     }
 
-    public static String getWin32ErrorMessage(IOException e) {
+    @CheckForNull
+    public static String getWin32ErrorMessage(@Nonnull IOException e) {
         return getWin32ErrorMessage((Throwable)e);
     }
 
@@ -395,6 +405,7 @@ public class Util {
      * @return
      *      null if there seems to be no error code or if the platform is not Win32.
      */
+    @CheckForNull
     public static String getWin32ErrorMessage(Throwable e) {
         String msg = e.getMessage();
         if(msg!=null) {
@@ -420,6 +431,7 @@ public class Util {
      * @return
      *      null if no such message is available.
      */
+    @CheckForNull
     public static String getWin32ErrorMessage(int n) {
         try {
             ResourceBundle rb = ResourceBundle.getBundle("/hudson/win32errors");
@@ -433,6 +445,7 @@ public class Util {
     /**
      * Guesses the current host name.
      */
+    @Nonnull
     public static String getHostName() {
         try {
             return InetAddress.getLocalHost().getHostName();
@@ -441,21 +454,21 @@ public class Util {
         }
     }
 
-    public static void copyStream(InputStream in,OutputStream out) throws IOException {
+    public static void copyStream(@Nonnull InputStream in,@Nonnull OutputStream out) throws IOException {
         byte[] buf = new byte[8192];
         int len;
         while((len=in.read(buf))>=0)
             out.write(buf,0,len);
     }
 
-    public static void copyStream(Reader in, Writer out) throws IOException {
+    public static void copyStream(@Nonnull Reader in, @Nonnull Writer out) throws IOException {
         char[] buf = new char[8192];
         int len;
         while((len=in.read(buf))>0)
             out.write(buf,0,len);
     }
 
-    public static void copyStreamAndClose(InputStream in,OutputStream out) throws IOException {
+    public static void copyStreamAndClose(@Nonnull InputStream in, @Nonnull OutputStream out) throws IOException {
         try {
             copyStream(in,out);
         } finally {
@@ -464,7 +477,7 @@ public class Util {
         }
     }
 
-    public static void copyStreamAndClose(Reader in,Writer out) throws IOException {
+    public static void copyStreamAndClose(@Nonnull Reader in, @Nonnull Writer out) throws IOException {
         try {
             copyStream(in,out);
         } finally {
@@ -483,18 +496,21 @@ public class Util {
      * @since 1.145
      * @see QuotedStringTokenizer
      */
-    public static String[] tokenize(String s,String delimiter) {
+    @Nonnull
+    public static String[] tokenize(@Nonnull String s, @CheckForNull String delimiter) {
         return QuotedStringTokenizer.tokenize(s,delimiter);
     }
 
-    public static String[] tokenize(String s) {
+    @Nonnull
+    public static String[] tokenize(@Nonnull String s) {
         return tokenize(s," \t\n\r\f");
     }
 
     /**
      * Converts the map format of the environment variables to the K=V format in the array.
      */
-    public static String[] mapToEnv(Map<String,String> m) {
+    @Nonnull
+    public static String[] mapToEnv(@Nonnull Map<String,String> m) {
         String[] r = new String[m.size()];
         int idx=0;
 
@@ -504,7 +520,7 @@ public class Util {
         return r;
     }
 
-    public static int min(int x, int... values) {
+    public static int min(int x, @Nonnull int... values) {
         for (int i : values) {
             if(i<x)
                 x=i;
@@ -512,11 +528,13 @@ public class Util {
         return x;
     }
 
-    public static String nullify(String v) {
+    @CheckForNull
+    public static String nullify(@CheckForNull String v) {
         return fixEmpty(v);
     }
 
-    public static String removeTrailingSlash(String s) {
+    @Nonnull
+    public static String removeTrailingSlash(@Nonnull String s) {
         if(s.endsWith("/")) return s.substring(0,s.length()-1);
         else                return s;
     }
@@ -531,7 +549,8 @@ public class Util {
      *         case subject was null and subject + suffix otherwise.
      * @since 1.505
      */
-    public static String ensureEndsWith(String subject, String suffix) {
+    @Nullable
+    public static String ensureEndsWith(@CheckForNull String subject, @CheckForNull String suffix) {
 
         if (subject == null) return null;
 
@@ -549,7 +568,8 @@ public class Util {
      *      32-char wide string
      * @see DigestUtils#md5Hex(InputStream)
      */
-    public static String getDigestOf(InputStream source) throws IOException {
+    @Nonnull
+    public static String getDigestOf(@Nonnull InputStream source) throws IOException {
         try {
             MessageDigest md5 = MessageDigest.getInstance("MD5");
 
@@ -574,7 +594,8 @@ public class Util {
         */
     }
 
-    public static String getDigestOf(String text) {
+    @Nonnull
+    public static String getDigestOf(@Nonnull String text) {
         try {
             return getDigestOf(new ByteArrayInputStream(text.getBytes("UTF-8")));
         } catch (IOException e) {
@@ -589,7 +610,8 @@ public class Util {
      * @throws IOException in case reading fails
      * @since 1.525
      */
-    public static String getDigestOf(File file) throws IOException {
+    @Nonnull
+    public static String getDigestOf(@Nonnull File file) throws IOException {
         InputStream is = new FileInputStream(file);
         try {
             return getDigestOf(new BufferedInputStream(is));
@@ -602,7 +624,8 @@ public class Util {
      * Converts a string into 128-bit AES key.
      * @since 1.308
      */
-    public static SecretKey toAes128Key(String s) {
+    @Nonnull 
+    public static SecretKey toAes128Key(@Nonnull String s) {
         try {
             // turn secretKey into 256 bit hash
             MessageDigest digest = MessageDigest.getInstance("SHA-256");
@@ -618,7 +641,8 @@ public class Util {
         }
     }
 
-    public static String toHexString(byte[] data, int start, int len) {
+    @Nonnull
+    public static String toHexString(@Nonnull byte[] data, int start, int len) {
         StringBuilder buf = new StringBuilder();
         for( int i=0; i<len; i++ ) {
             int b = data[start+i]&0xFF;
@@ -628,11 +652,13 @@ public class Util {
         return buf.toString();
     }
 
-    public static String toHexString(byte[] bytes) {
+    @Nonnull
+    public static String toHexString(@Nonnull byte[] bytes) {
         return toHexString(bytes,0,bytes.length);
     }
 
-    public static byte[] fromHexString(String data) {
+    @Nonnull
+    public static byte[] fromHexString(@Nonnull String data) {
         byte[] r = new byte[data.length() / 2];
         for (int i = 0; i < data.length(); i += 2)
             r[i / 2] = (byte) Integer.parseInt(data.substring(i, i + 2), 16);
@@ -646,6 +672,7 @@ public class Util {
      * @param duration
      *      number of milliseconds.
      */
+    @Nonnull
     public static String getTimeSpanString(long duration) {
         // Break the duration up in to units.
         long years = duration / ONE_YEAR_MS;
@@ -692,10 +719,11 @@ public class Util {
      * So 13 minutes and 43 seconds returns just "13 minutes", but 3 minutes
      * and 43 seconds is "3 minutes 43 seconds".
      */
+    @Nonnull
     private static String makeTimeSpanString(long bigUnit,
-                                             String bigLabel,
+                                             @Nonnull String bigLabel,
                                              long smallUnit,
-                                             String smallLabel) {
+                                             @Nonnull String smallLabel) {
         String text = bigLabel;
         if (bigUnit < 10)
             text += ' ' + smallLabel;
@@ -707,6 +735,7 @@ public class Util {
      * Get a human readable string representing strings like "xxx days ago",
      * which should be used to point to the occurrence of an event in the past.
      */
+    @Nonnull
     public static String getPastTimeString(long duration) {
         return Messages.Util_pastTime(getTimeSpanString(duration));
     }
@@ -720,7 +749,8 @@ public class Util {
      *   See {@link Messages#Util_year(Object)} for an example.
      *   Deprecated since 2009-06-24, remove method after 2009-12-24.
      */
-    public static String combine(long n, String suffix) {
+    @Nonnull
+    public static String combine(long n, @Nonnull String suffix) {
         String s = Long.toString(n)+' '+suffix;
         if(n!=1)
         	// Just adding an 's' won't work in most natural languages, even English has exception to the rule (e.g. copy/copies).
@@ -731,7 +761,8 @@ public class Util {
     /**
      * Create a sub-list by only picking up instances of the specified type.
      */
-    public static <T> List<T> createSubList( Collection<?> source, Class<T> type ) {
+    @Nonnull
+    public static <T> List<T> createSubList(@Nonnull Collection<?> source, @Nonnull Class<T> type ) {
         List<T> r = new ArrayList<T>();
         for (Object item : source) {
             if(type.isInstance(item))
@@ -749,7 +780,8 @@ public class Util {
      * {@link #rawEncode(String)} should generally be used instead, though be careful to pass only
      * a single path component to that method (it will encode /, but this method does not).
      */
-    public static String encode(String s) {
+    @Nonnull 
+    public static String encode(@Nonnull String s) {
         try {
             boolean escaped = false;
 
@@ -806,7 +838,8 @@ public class Util {
      * single path component used in constructing a URL.
      * Method name inspired by PHP's rawurlencode.
      */
-    public static String rawEncode(String s) {
+    @Nonnull
+    public static String rawEncode(@Nonnull String s) {
         boolean escaped = false;
         StringBuilder out = null;
         CharsetEncoder enc = null;
@@ -855,7 +888,8 @@ public class Util {
     /**
      * Escapes HTML unsafe characters like &lt;, &amp; to the respective character entities.
      */
-    public static String escape(String text) {
+    @Nonnull 
+    public static String escape(@Nonnull String text) {
         if (text==null)     return null;
         StringBuilder buf = new StringBuilder(text.length()+64);
         for( int i=0; i<text.length(); i++ ) {
@@ -888,7 +922,8 @@ public class Util {
         return buf.toString();
     }
 
-    public static String xmlEscape(String text) {
+    @Nonnull
+    public static String xmlEscape(@Nonnull String text) {
         StringBuilder buf = new StringBuilder(text.length()+64);
         for( int i=0; i<text.length(); i++ ) {
             char ch = text.charAt(i);
@@ -906,14 +941,14 @@ public class Util {
     /**
      * Creates an empty file.
      */
-    public static void touch(File file) throws IOException {
+    public static void touch(@Nonnull File file) throws IOException {
         new FileOutputStream(file).close();
     }
 
     /**
      * Copies a single file by using Ant.
      */
-    public static void copyFile(File src, File dst) throws BuildException {
+    public static void copyFile(@Nonnull File src, @Nonnull File dst) throws BuildException {
         Copy cp = new Copy();
         cp.setProject(new org.apache.tools.ant.Project());
         cp.setTofile(dst);
@@ -925,7 +960,8 @@ public class Util {
     /**
      * Convert null to "".
      */
-    public static String fixNull(String s) {
+    @Nonnull
+    public static String fixNull(@CheckForNull String s) {
         if(s==null)     return "";
         else            return s;
     }
@@ -933,7 +969,8 @@ public class Util {
     /**
      * Convert empty string to null.
      */
-    public static String fixEmpty(String s) {
+    @CheckForNull
+    public static String fixEmpty(@CheckForNull String s) {
         if(s==null || s.length()==0)    return null;
         return s;
     }
@@ -943,31 +980,37 @@ public class Util {
      *
      * @since 1.154
      */
-    public static String fixEmptyAndTrim(String s) {
+    @CheckForNull
+    public static String fixEmptyAndTrim(@CheckForNull String s) {
         if(s==null)    return null;
         return fixEmpty(s.trim());
     }
 
-    public static <T> List<T> fixNull(List<T> l) {
+    @Nonnull
+    public static <T> List<T> fixNull(@CheckForNull List<T> l) {
         return l!=null ? l : Collections.<T>emptyList();
     }
 
-    public static <T> Set<T> fixNull(Set<T> l) {
+    @Nonnull
+    public static <T> Set<T> fixNull(@CheckForNull Set<T> l) {
         return l!=null ? l : Collections.<T>emptySet();
     }
 
-    public static <T> Collection<T> fixNull(Collection<T> l) {
+    @Nonnull
+    public static <T> Collection<T> fixNull(@CheckForNull Collection<T> l) {
         return l!=null ? l : Collections.<T>emptySet();
     }
 
-    public static <T> Iterable<T> fixNull(Iterable<T> l) {
+    @Nonnull
+    public static <T> Iterable<T> fixNull(@CheckForNull Iterable<T> l) {
         return l!=null ? l : Collections.<T>emptySet();
     }
 
     /**
      * Cuts all the leading path portion and get just the file name.
      */
-    public static String getFileName(String filePath) {
+    @Nonnull
+    public static String getFileName(@Nonnull String filePath) {
         int idx = filePath.lastIndexOf('\\');
         if(idx>=0)
             return getFileName(filePath.substring(idx+1));
@@ -980,7 +1023,8 @@ public class Util {
     /**
      * Concatenate multiple strings by inserting a separator.
      */
-    public static String join(Collection<?> strings, String separator) {
+    @Nonnull
+    public static String join(@Nonnull Collection<?> strings, @Nonnull String separator) {
         StringBuilder buf = new StringBuilder();
         boolean first=true;
         for (Object s : strings) {
@@ -994,7 +1038,8 @@ public class Util {
     /**
      * Combines all the given collections into a single list.
      */
-    public static <T> List<T> join(Collection<? extends T>... items) {
+    @Nonnull
+    public static <T> List<T> join(@Nonnull Collection<? extends T>... items) {
         int size = 0;
         for (Collection<? extends T> item : items)
             size += item.size();
@@ -1021,7 +1066,8 @@ public class Util {
      *      Can be null.
      * @since 1.172
      */
-    public static FileSet createFileSet(File baseDir, String includes, String excludes) {
+    @Nonnull
+    public static FileSet createFileSet(@Nonnull File baseDir, @Nonnull String includes, @CheckForNull String excludes) {
         FileSet fs = new FileSet();
         fs.setDir(baseDir);
         fs.setProject(new Project());
@@ -1043,7 +1089,8 @@ public class Util {
         return fs;
     }
 
-    public static FileSet createFileSet(File baseDir, String includes) {
+    @Nonnull
+    public static FileSet createFileSet(@Nonnull File baseDir, @Nonnull String includes) {
         return createFileSet(baseDir,includes,null);
     }
 
@@ -1059,7 +1106,8 @@ public class Util {
      * @param symlinkPath
      *      Where to create a symlink in (relative to {@code baseDir})
      */
-    public static void createSymlink(File baseDir, String targetPath, String symlinkPath, TaskListener listener) throws InterruptedException {
+    public static void createSymlink(@Nonnull File baseDir, @Nonnull String targetPath, 
+            @Nonnull String symlinkPath, @Nonnull TaskListener listener) throws InterruptedException {
         try {
             if (createSymlinkJava7(baseDir, targetPath, symlinkPath)) {
                 return;
@@ -1131,7 +1179,7 @@ public class Util {
         }
     }
 
-    private static boolean createSymlinkJava7(File baseDir, String targetPath, String symlinkPath) throws IOException {
+    private static boolean createSymlinkJava7(@Nonnull File baseDir, @Nonnull String targetPath, @Nonnull String symlinkPath) throws IOException {
         try {
             Object path = File.class.getMethod("toPath").invoke(new File(baseDir, symlinkPath));
             Object target = Class.forName("java.nio.file.Paths").getMethod("get", String.class, String[].class).invoke(null, targetPath, new String[0]);
@@ -1201,7 +1249,8 @@ public class Util {
      * @return null
      *      if the specified file is not a symlink.
      */
-    public static File resolveSymlinkToFile(File link) throws InterruptedException, IOException {
+    @CheckForNull
+    public static File resolveSymlinkToFile(@Nonnull File link) throws InterruptedException, IOException {
         String target = resolveSymlink(link);
         if (target==null)   return null;
 
@@ -1221,7 +1270,8 @@ public class Util {
      *      If the symlink is relative, the returned string is that relative representation.
      *      The relative path is meant to be resolved from the location of the symlink.
      */
-    public static String resolveSymlink(File link) throws InterruptedException, IOException {
+    @CheckForNull
+    public static String resolveSymlink(@Nonnull File link) throws InterruptedException, IOException {
         try { // Java 7
             Object path = File.class.getMethod("toPath").invoke(link);
             return Class.forName("java.nio.file.Files").getMethod("readSymbolicLink", Class.forName("java.nio.file.Path")).invoke(null, path).toString();
@@ -1306,7 +1356,8 @@ public class Util {
      * Wraps with the error icon and the CSS class to render error message.
      * @since 1.173
      */
-    public static String wrapToErrorSpan(String s) {
+    @Nonnull
+    public static String wrapToErrorSpan(@Nonnull String s) {
         s = "<span class=error style='display:inline-block'>"+s+"</span>";
         return s;
     }
@@ -1319,7 +1370,8 @@ public class Util {
      * @param defaultNumber number to return if the string can not be parsed
      * @return returns the parsed string; otherwise the default number
      */
-    public static Number tryParseNumber(String numberStr, Number defaultNumber) {
+    @CheckForNull
+    public static Number tryParseNumber(@CheckForNull String numberStr, @CheckForNull Number defaultNumber) {
         if ((numberStr == null) || (numberStr.length() == 0)) {
             return defaultNumber;
         }
@@ -1334,7 +1386,7 @@ public class Util {
      * Checks if the public method defined on the base type with the given arguments
      * are overridden in the given derived type.
      */
-    public static boolean isOverridden(Class base, Class derived, String methodName, Class... types) {
+    public static boolean isOverridden(@Nonnull Class base, @Nonnull Class derived, @Nonnull String methodName, @Nonnull Class... types) {
         try {
             return !base.getMethod(methodName, types).equals(
                     derived.getMethod(methodName,types));
@@ -1349,7 +1401,8 @@ public class Util {
      * @param ext
      *      For example, ".zip"
      */
-    public static File changeExtension(File dst, String ext) {
+    @Nonnull
+    public static File changeExtension(@Nonnull File dst, @Nonnull String ext) {
         String p = dst.getPath();
         int pos = p.lastIndexOf('.');
         if (pos<0)  return new File(p+ext);
@@ -1358,8 +1411,10 @@ public class Util {
 
     /**
      * Null-safe String intern method.
+     * @return A canonical representation for the string object. Null for null input strings
      */
-    public static String intern(String s) {
+    @Nullable
+    public static String intern(@CheckForNull String s) {
         return s==null ? s : s.intern();
     }
 
@@ -1370,7 +1425,7 @@ public class Util {
      * implementing this by ourselves allow it to be more lenient about
      * escaping of URI.
      */
-    public static boolean isAbsoluteUri(String uri) {
+    public static boolean isAbsoluteUri(@Nonnull String uri) {
         int idx = uri.indexOf(':');
         if (idx<0)  return false;   // no ':'. can't be absolute
 
@@ -1382,7 +1437,7 @@ public class Util {
      * Works like {@link String#indexOf(int)} but 'not found' is returned as s.length(), not -1.
      * This enables more straight-forward comparison.
      */
-    private static int _indexOf(String s, char ch) {
+    private static int _indexOf(@Nonnull String s, char ch) {
         int idx = s.indexOf(ch);
         if (idx<0)  return s.length();
         return idx;
@@ -1392,7 +1447,8 @@ public class Util {
      * Loads a key/value pair string as {@link Properties}
      * @since 1.392
      */
-    public static Properties loadProperties(String properties) throws IOException {
+    @Nonnull
+    public static Properties loadProperties(@Nonnull String properties) throws IOException {
         Properties p = new Properties();
         p.load(new StringReader(properties));
         return p;
diff --git a/core/src/main/java/hudson/cli/InstallToolCommand.java b/core/src/main/java/hudson/cli/InstallToolCommand.java
index fb30efd0c08b52798e618e95f1dce303aefca908..f5ad164f95e2a6dcbf5ad0e9d49160fce2f5fb3e 100644
--- a/core/src/main/java/hudson/cli/InstallToolCommand.java
+++ b/core/src/main/java/hudson/cli/InstallToolCommand.java
@@ -122,6 +122,9 @@ public class InstallToolCommand extends CLICommand {
             throw new AbortException(b.getFullDisplayName()+" is not building");
 
         Node node = exec.getOwner().getNode();
+        if (node == null) {
+            throw new AbortException("The node " + exec.getOwner().getDisplayName() + " has been deleted");
+        }
 
         t = t.translate(node, EnvVars.getRemote(checkChannel()), new StreamTaskListener(stderr));
         stdout.println(t.getHome());
diff --git a/core/src/main/java/hudson/model/AbstractBuild.java b/core/src/main/java/hudson/model/AbstractBuild.java
index aec68e72efee334306e237b8c4e112f346c6e9bd..14fe40daedc95a2d06e58398f01282dca98ba533 100644
--- a/core/src/main/java/hudson/model/AbstractBuild.java
+++ b/core/src/main/java/hudson/model/AbstractBuild.java
@@ -84,9 +84,11 @@ import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
 import org.kohsuke.stapler.interceptor.RequirePOST;
 
 import static java.util.logging.Level.WARNING;
+
 import jenkins.model.lazy.BuildReference;
 import jenkins.model.lazy.LazyBuildMixIn;
 
@@ -435,9 +437,20 @@ public abstract class AbstractBuild<P extends AbstractProject<P,R>,R extends Abs
 
         /**
          * Returns the current {@link Node} on which we are building.
+         * @return Returns the current {@link Node}
+         * @throws IllegalStateException if that cannot be determined
          */
-        protected final Node getCurrentNode() {
-            return Executor.currentExecutor().getOwner().getNode();
+        protected final @Nonnull Node getCurrentNode() throws IllegalStateException {
+            Executor exec = Executor.currentExecutor();
+            if (exec == null) {
+                throw new IllegalStateException("not being called from an executor thread");
+            }
+            Computer c = exec.getOwner();
+            Node node = c.getNode();
+            if (node == null) {
+                throw new IllegalStateException("no longer a configured node for " + c.getName());
+            }
+            return node;
         }
 
         public Launcher getLauncher() {
@@ -456,7 +469,7 @@ public abstract class AbstractBuild<P extends AbstractProject<P,R>,R extends Abs
          * @param wsl
          *      Passed in for the convenience. The returned path must be registered to this object.
          */
-        protected Lease decideWorkspace(Node n, WorkspaceList wsl) throws InterruptedException, IOException {
+        protected Lease decideWorkspace(@Nonnull Node n, WorkspaceList wsl) throws InterruptedException, IOException {
             String customWorkspace = getProject().getCustomWorkspace();
             if (customWorkspace != null) {
                 // we allow custom workspaces to be concurrently used between jobs.
@@ -466,8 +479,9 @@ public abstract class AbstractBuild<P extends AbstractProject<P,R>,R extends Abs
             return wsl.allocate(n.getWorkspaceFor((TopLevelItem)getProject()), getBuild());
         }
 
-        public Result run(BuildListener listener) throws Exception {
-            Node node = getCurrentNode();
+        public Result run(@Nonnull BuildListener listener) throws Exception {
+            final Node node = getCurrentNode();
+            
             assert builtOn==null;
             builtOn = node.getNodeName();
             hudsonVersion = Jenkins.VERSION;
@@ -555,8 +569,10 @@ public abstract class AbstractBuild<P extends AbstractProject<P,R>,R extends Abs
          * @param listener
          *      Always non-null. Connected to the main build output.
          */
-        protected Launcher createLauncher(BuildListener listener) throws IOException, InterruptedException {
-            Launcher l = getCurrentNode().createLauncher(listener);
+        @Nonnull
+        protected Launcher createLauncher(@Nonnull BuildListener listener) throws IOException, InterruptedException {
+            final Node currentNode = getCurrentNode();
+            Launcher l = currentNode.createLauncher(listener);
 
             if (project instanceof BuildableItemWithBuildWrappers) {
                 BuildableItemWithBuildWrappers biwbw = (BuildableItemWithBuildWrappers) project;
@@ -580,7 +596,7 @@ public abstract class AbstractBuild<P extends AbstractProject<P,R>,R extends Abs
                 }
             }
 
-            for (NodeProperty nodeProperty: Computer.currentComputer().getNode().getNodeProperties()) {
+            for (NodeProperty nodeProperty: currentNode.getNodeProperties()) {
                 Environment environment = nodeProperty.setUp(AbstractBuild.this, l, listener);
                 if (environment != null) {
                     buildEnvironments.add(environment);
diff --git a/core/src/main/java/hudson/model/AbstractCIBase.java b/core/src/main/java/hudson/model/AbstractCIBase.java
index 11b1c7cff876557e6167ff904e3950ae6244003d..08254d78082ea6b9cf0e4487bafdfd4d4b297a90 100644
--- a/core/src/main/java/hudson/model/AbstractCIBase.java
+++ b/core/src/main/java/hudson/model/AbstractCIBase.java
@@ -165,9 +165,10 @@ public abstract class AbstractCIBase extends Node implements ItemGroup<TopLevelI
         synchronized(updateComputerLock) {// just so that we don't have two code updating computer list at the same time
             Map<String,Computer> byName = new HashMap<String,Computer>();
             for (Computer c : computers.values()) {
-                if(c.getNode()==null)
+                Node node = c.getNode();
+                if (node == null)
                     continue;   // this computer is gone
-                byName.put(c.getNode().getNodeName(),c);
+                byName.put(node.getNodeName(),c);
             }
 
             Set<Computer> old = new HashSet<Computer>(computers.values());
diff --git a/core/src/main/java/hudson/model/Api.java b/core/src/main/java/hudson/model/Api.java
index 71b617e46f8c85951bc1dae2ca642737dda2e660..ff84f4b66d2a9ce39bc82ceac11963fd43e77c8f 100644
--- a/core/src/main/java/hudson/model/Api.java
+++ b/core/src/main/java/hudson/model/Api.java
@@ -154,16 +154,21 @@ public class Api extends AbstractModelObject {
             throw new IOException("Failed to do XPath/wrapper handling. Turn on FINER logging to view XML.",e);
         }
 
+
+        if (isSimpleOutput(result) && !permit(req)) {
+            // simple output prohibited
+            rsp.sendError(HttpURLConnection.HTTP_FORBIDDEN, "primitive XPath result sets forbidden; implement jenkins.security.SecureRequester");
+            return;
+        }
+
+        // switch to gzipped output
         OutputStream o = rsp.getCompressedOutputStream(req);
         try {
-            if (result instanceof CharacterData || result instanceof String || result instanceof Number || result instanceof Boolean) {
-                if (permit(req)) {
-                    rsp.setContentType("text/plain;charset=UTF-8");
-                    String text = result instanceof CharacterData ? ((CharacterData) result).getText() : result.toString();
-                    o.write(text.getBytes("UTF-8"));
-                } else {
-                    rsp.sendError(HttpURLConnection.HTTP_FORBIDDEN, "primitive XPath result sets forbidden; implement jenkins.security.SecureRequester");
-                }
+            if (isSimpleOutput(result)) {
+                // simple output allowed
+                rsp.setContentType("text/plain;charset=UTF-8");
+                String text = result instanceof CharacterData ? ((CharacterData) result).getText() : result.toString();
+                o.write(text.getBytes("UTF-8"));
                 return;
             }
 
@@ -175,6 +180,10 @@ public class Api extends AbstractModelObject {
         }
     }
 
+    private boolean isSimpleOutput(Object result) {
+        return result instanceof CharacterData || result instanceof String || result instanceof Number || result instanceof Boolean;
+    }
+
     /**
      * Generate schema.
      */
diff --git a/core/src/main/java/hudson/model/Build.java b/core/src/main/java/hudson/model/Build.java
index 53cbf82af7bcfc575f0e96198e3b2a8018d5970c..99073f1b7332b5eccc737e2eea1edd55ed5f9a14 100644
--- a/core/src/main/java/hudson/model/Build.java
+++ b/core/src/main/java/hudson/model/Build.java
@@ -42,6 +42,7 @@ import java.util.logging.Logger;
 import java.util.logging.Level;
 
 import static hudson.model.Result.FAILURE;
+import javax.annotation.Nonnull;
 
 /**
  * A build of a {@link Project}.
@@ -135,7 +136,7 @@ public abstract class Build <P extends Project<P,B>,B extends Build<P,B>>
             deprecated class here.
          */
 
-        protected Result doRun(BuildListener listener) throws Exception {
+        protected Result doRun(@Nonnull BuildListener listener) throws Exception {
             if(!preBuild(listener,project.getBuilders()))
                 return FAILURE;
             if(!preBuild(listener,project.getPublishersList()))
@@ -178,7 +179,7 @@ public abstract class Build <P extends Project<P,B>,B extends Build<P,B>>
             return r;
         }
 
-        public void post2(BuildListener listener) throws IOException, InterruptedException {
+        public void post2(@Nonnull BuildListener listener) throws IOException, InterruptedException {
             if (!performAllBuildSteps(listener, project.getPublishersList(), true))
                 setResult(FAILURE);
             if (!performAllBuildSteps(listener, project.getProperties(), true))
@@ -186,14 +187,14 @@ public abstract class Build <P extends Project<P,B>,B extends Build<P,B>>
         }
 
         @Override
-        public void cleanUp(BuildListener listener) throws Exception {
+        public void cleanUp(@Nonnull BuildListener listener) throws Exception {
             // at this point it's too late to mark the build as a failure, so ignore return value.
             performAllBuildSteps(listener, project.getPublishersList(), false);
             performAllBuildSteps(listener, project.getProperties(), false);
             super.cleanUp(listener);
         }
 
-        private boolean build(BuildListener listener, Collection<Builder> steps) throws IOException, InterruptedException {
+        private boolean build(@Nonnull BuildListener listener, @Nonnull Collection<Builder> steps) throws IOException, InterruptedException {
             for( BuildStep bs : steps ) {
                 if(!perform(bs,listener)) {
                     LOGGER.log(Level.FINE, "{0} : {1} failed", new Object[] {Build.this, bs});
diff --git a/core/src/main/java/hudson/model/Computer.java b/core/src/main/java/hudson/model/Computer.java
index 86fbb6c0ea5381728f2c07a32c11571092f73e97..33e272171261d82d24fb940e22b9e05adc91d080 100644
--- a/core/src/main/java/hudson/model/Computer.java
+++ b/core/src/main/java/hudson/model/Computer.java
@@ -204,7 +204,7 @@ public /*transient*/ abstract class Computer extends Actionable implements Acces
 
     /**
      * This is where the log from the remote agent goes.
-     *
+     * The method also creates a log directory if required.
      * @see #relocateOldLogs()
      */
     protected File getLogFile() {
@@ -1196,7 +1196,11 @@ public /*transient*/ abstract class Computer extends Actionable implements Acces
             // read
             checkPermission(EXTENDED_READ);
             rsp.setContentType("application/xml");
-            Jenkins.XSTREAM2.toXMLUTF8(getNode(), rsp.getOutputStream());
+            Node node = getNode();
+            if (node == null) {
+                throw HttpResponses.notFound();
+            }
+            Jenkins.XSTREAM2.toXMLUTF8(node, rsp.getOutputStream());
             return;
         }
         if (req.getMethod().equals("POST")) {
@@ -1218,7 +1222,8 @@ public /*transient*/ abstract class Computer extends Actionable implements Acces
         // replace the old Node object by the new one
         synchronized (app) {
             List<Node> nodes = new ArrayList<Node>(app.getNodes());
-            int i = nodes.indexOf(getNode());
+            Node node = getNode();
+            int i  = (node != null) ? nodes.indexOf(node) : -1;
             if(i<0) {
                 throw new IOException("This slave appears to be removed while you were editing the configuration");
             }
@@ -1348,7 +1353,12 @@ public /*transient*/ abstract class Computer extends Actionable implements Acces
             if (m.matches()) {
                 File newLocation = new File(dir, "logs/slaves/" + m.group(1) + "/slave.log" + Util.fixNull(m.group(2)));
                 newLocation.getParentFile().mkdirs();
-                f.renameTo(newLocation);
+                boolean relocationSuccessfull=f.renameTo(newLocation);
+                if (relocationSuccessfull) { // The operation will fail if mkdir fails 
+                    LOGGER.log(Level.INFO, "Relocated log file {0} to {1}",new Object[] {f.getPath(),newLocation.getPath()});
+                } else {
+                    LOGGER.log(Level.WARNING, "Cannot relocate log file {0} to {1}",new Object[] {f.getPath(),newLocation.getPath()});
+                }
             } else {
                 assert false;
             }
diff --git a/core/src/main/java/hudson/model/Executor.java b/core/src/main/java/hudson/model/Executor.java
index e0cfe64ed71f09a4d0917e446beb1cd10af52e8e..4353ad754626c0bd7759f8dcf3160d2d8a5b5d18 100644
--- a/core/src/main/java/hudson/model/Executor.java
+++ b/core/src/main/java/hudson/model/Executor.java
@@ -59,6 +59,7 @@ import java.util.logging.Logger;
 import static hudson.model.queue.Executables.*;
 import static java.util.logging.Level.*;
 import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
 
 
 /**
@@ -70,7 +71,7 @@ import javax.annotation.CheckForNull;
  */
 @ExportedBean
 public class Executor extends Thread implements ModelObject {
-    protected final Computer owner;
+    protected final @Nonnull Computer owner;
     private final Queue queue;
 
     private long startTime;
@@ -111,7 +112,7 @@ public class Executor extends Thread implements ModelObject {
      */
     private final List<CauseOfInterruption> causes = new Vector<CauseOfInterruption>();
 
-    public Executor(Computer owner, int n) {
+    public Executor(@Nonnull Computer owner, int n) {
         super("Executor #"+n+" for "+owner.getDisplayName());
         this.owner = owner;
         this.queue = Jenkins.getInstance().getQueue();
@@ -534,7 +535,7 @@ public class Executor extends Thread implements ModelObject {
         return e!=null && Tasks.getOwnerTaskOf(getParentOf(e)).hasAbortPermission();
     }
 
-    public Computer getOwner() {
+    public @Nonnull Computer getOwner() {
         return owner;
     }
 
diff --git a/core/src/main/java/hudson/model/Node.java b/core/src/main/java/hudson/model/Node.java
index fe9fbe08419e73769ea3af64e85b3c703a5224fd..e78b2cd5e86b2f53bbdf5d1e041c20675627312b 100644
--- a/core/src/main/java/hudson/model/Node.java
+++ b/core/src/main/java/hudson/model/Node.java
@@ -202,7 +202,7 @@ public abstract class Node extends AbstractModelObject implements Reconfigurable
             // At startup, we need to restore any previously in-effect temp offline cause.
             // We wait until the computer is started rather than getting the data to it sooner
             // so that the normal computer start up processing works as expected.
-            if (node.temporaryOfflineCause != null && node.temporaryOfflineCause != c.getOfflineCause()) {
+            if (node!= null && node.temporaryOfflineCause != null && node.temporaryOfflineCause != c.getOfflineCause()) {
                 c.setTemporarilyOffline(true, node.temporaryOfflineCause);
             }
         }
diff --git a/core/src/main/java/hudson/model/Queue.java b/core/src/main/java/hudson/model/Queue.java
index 518be29e47caf54f26d79bbc00269fbb60457b9e..c1e4bfa0c8c02cde9ab1f3291f92ab516d84ac0d 100644
--- a/core/src/main/java/hudson/model/Queue.java
+++ b/core/src/main/java/hudson/model/Queue.java
@@ -283,6 +283,7 @@ public class Queue extends ResourceController implements Saveable {
             return workUnit == null && !executor.getOwner().isOffline() && executor.getOwner().isAcceptingTasks();
         }
 
+        @CheckForNull
         public Node getNode() {
             return executor.getOwner().getNode();
         }
@@ -739,6 +740,8 @@ public class Queue extends ResourceController implements Saveable {
 
     private void _getBuildableItems(Computer c, ItemList<BuildableItem> col, List<BuildableItem> result) {
         Node node = c.getNode();
+        if (node == null)   // Deleted computers cannot take build items... 
+            return;
         for (BuildableItem p : col.values()) {
             if (node.canTake(p) == null)
                 result.add(p);
diff --git a/core/src/main/java/hudson/model/Run.java b/core/src/main/java/hudson/model/Run.java
index ee4cd8f56b45a7b39211df49668e8cb41bcb8369..bb3873ecbff545ab0689903b9c512235bf4d707c 100644
--- a/core/src/main/java/hudson/model/Run.java
+++ b/core/src/main/java/hudson/model/Run.java
@@ -111,6 +111,7 @@ import jenkins.model.lazy.BuildReference;
 import jenkins.util.VirtualFile;
 import jenkins.util.io.OnMaster;
 import net.sf.json.JSONObject;
+import org.acegisecurity.AccessDeniedException;
 import org.acegisecurity.Authentication;
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.jelly.XMLOutput;
@@ -136,7 +137,7 @@ import org.kohsuke.stapler.interceptor.RequirePOST;
 public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,RunT>>
         extends Actionable implements ExtensionPoint, Comparable<RunT>, AccessControlled, PersistenceRoot, DescriptorByNameOwner, OnMaster {
 
-    protected transient final JobT project;
+    protected transient final @Nonnull JobT project;
 
     /**
      * Build number.
@@ -278,8 +279,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Creates a new {@link Run}.
+     * @param job Owner job
      */
-    protected Run(JobT job) throws IOException {
+    protected Run(@Nonnull JobT job) throws IOException {
         this(job, new GregorianCalendar());
         this.number = project.assignBuildNumber();
         LOGGER.log(FINER, "new {0} @{1}", new Object[] {this, hashCode()});
@@ -289,11 +291,11 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Constructor for creating a {@link Run} object in
      * an arbitrary state.
      */
-    protected Run(JobT job, Calendar timestamp) {
+    protected Run(@Nonnull JobT job, @Nonnull Calendar timestamp) {
         this(job,timestamp.getTimeInMillis());
     }
 
-    protected Run(JobT job, long timestamp) {
+    protected Run(@Nonnull JobT job, long timestamp) {
         this.project = job;
         this.timestamp = timestamp;
         this.state = State.NOT_STARTED;
@@ -303,7 +305,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * Loads a run from a log file.
      */
-    protected Run(JobT project, File buildDir) throws IOException {
+    protected Run(@Nonnull JobT project, @Nonnull File buildDir) throws IOException {
         this(project, parseTimestampFromBuildDir(buildDir));
         this.previousBuildInProgress = _this(); // loaded builds are always completed
         reload();
@@ -357,8 +359,13 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     public List<Action> getTransientActions() {
         List<Action> actions = new ArrayList<Action>();
         for (TransientBuildActionFactory factory: TransientBuildActionFactory.all()) {
-            actions.addAll(factory.createFor(this));
-            assert !actions.contains(null) : "null action added by " + factory;
+            for (Action created : factory.createFor(this)) {
+                if (created == null) {
+                    LOGGER.log(WARNING, "null action added by {0}", factory);
+                    continue;
+                }
+                actions.add(created);
+            }
         }
         return Collections.unmodifiableList(actions);
     }
@@ -369,7 +376,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      */
     @SuppressWarnings("deprecation")
     @Override
-    public void addAction(Action a) {
+    public void addAction(@Nonnull Action a) {
         super.addAction(a);
         if (a instanceof RunAction2) {
             ((RunAction2) a).onAttached(this);
@@ -384,7 +391,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         }
     }
 
-    /*package*/ static long parseTimestampFromBuildDir(File buildDir) throws IOException, InvalidDirectoryNameException {
+    /*package*/ static long parseTimestampFromBuildDir(@Nonnull File buildDir) 
+            throws IOException, InvalidDirectoryNameException {
         try {
             if(Util.isSymlink(buildDir)) {
                 // "Util.resolveSymlink(file)" resolves NTFS symlinks. 
@@ -406,16 +414,16 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Obtains 'this' in a more type safe signature.
-     */
+     */   
     @SuppressWarnings({"unchecked"})
-    protected RunT _this() {
+    protected @Nonnull RunT _this() {
         return (RunT)this;
     }
 
     /**
      * Ordering based on build numbers.
      */
-    public int compareTo(RunT that) {
+    public int compareTo(@Nonnull RunT that) {
         return this.number - that.number;
     }
 
@@ -432,7 +440,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         return result;
     }
 
-    public void setResult(Result r) {
+    public void setResult(@Nonnull Result r) {
         // state can change only when we are building
         assert state==State.BUILDING : state;
 
@@ -446,7 +454,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * Gets the subset of {@link #getActions()} that consists of {@link BuildBadgeAction}s.
      */
-    public List<BuildBadgeAction> getBadgeActions() {
+    public @Nonnull List<BuildBadgeAction> getBadgeActions() {
         List<BuildBadgeAction> r = getActions(BuildBadgeAction.class);
         if(isKeepLog()) {
             r.add(new KeepLogBuildBadge());
@@ -508,7 +516,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Otherwise null.
      * @since 1.433 
      */
-    public Executor getOneOffExecutor() {
+    public @CheckForNull Executor getOneOffExecutor() {
         for( Computer c : Jenkins.getInstance().getComputers() ) {
             for (Executor e : c.getOneOffExecutors()) {
                 if(e.getCurrentExecutable()==this)
@@ -522,14 +530,14 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Gets the charset in which the log file is written.
      * @return never null.
      * @since 1.257
-     */
-    public final Charset getCharset() {
+     */   
+    public final @Nonnull Charset getCharset() {
         if(charset==null)   return Charset.defaultCharset();
         return Charset.forName(charset);
     }
 
     /**
-     * Returns the {@link Cause}s that tirggered a build.
+     * Returns the {@link Cause}s that triggered a build.
      *
      * <p>
      * If a build sits in the queue for a long time, multiple build requests made during this period
@@ -539,7 +547,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      *      can be empty but never null. read-only.
      * @since 1.321
      */
-    public List<Cause> getCauses() {
+    public @Nonnull List<Cause> getCauses() {
         CauseAction a = getAction(CauseAction.class);
         if (a==null)    return Collections.emptyList();
         return Collections.unmodifiableList(a.getCauses());
@@ -549,8 +557,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Returns a {@link Cause} of a particular type.
      *
      * @since 1.362
-     */
-    public <T extends Cause> T getCause(Class<T> type) {
+     */ 
+    public @CheckForNull <T extends Cause> T getCause(Class<T> type) {
         for (Cause c : getCauses())
             if (type.isInstance(c))
                 return type.cast(c);
@@ -570,8 +578,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * If {@link #isKeepLog()} returns true, returns a short, human-readable
      * sentence that explains why it's being kept.
-     */
-    public String getWhyKeepLog() {
+     */ 
+    public @CheckForNull String getWhyKeepLog() {
         if(keepLog)
             return Messages.Run_MarkedExplicitly();
         return null;    // not marked at all
@@ -579,8 +587,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * The project this build is for.
-     */
-    public JobT getParent() {
+     */ 
+    public @Nonnull JobT getParent() {
         return project;
     }
 
@@ -588,9 +596,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * When the build is scheduled.
      *
      * @see #getStartTimeInMillis()
-     */
+     */   
     @Exported
-    public Calendar getTimestamp() {
+    public @Nonnull Calendar getTimestamp() {
         GregorianCalendar c = new GregorianCalendar();
         c.setTimeInMillis(timestamp);
         return c;
@@ -598,8 +606,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Same as {@link #getTimestamp()} but in a different type.
-     */
-    public final Date getTime() {
+     */   
+    public final @Nonnull Date getTime() {
         return new Date(timestamp);
     }
 
@@ -632,8 +640,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * Returns the length-limited description.
      * @return The length-limited description.
-     */
-    public String getTruncatedDescription() {
+     */   
+    public @Nonnull String getTruncatedDescription() {
         final int maxDescrLength = 100;
         if (description == null || description.length() < maxDescrLength) {
             return description;
@@ -684,7 +692,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * @return
      *      string like "3 minutes" "1 day" etc.
      */
-    public String getTimestampString() {
+    public @Nonnull String getTimestampString() {
         long duration = new GregorianCalendar().getTimeInMillis()-timestamp;
         return Util.getPastTimeString(duration);
     }
@@ -692,14 +700,14 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * Returns the timestamp formatted in xs:dateTime.
      */
-    public String getTimestampString2() {
+    public @Nonnull String getTimestampString2() {
         return Util.XS_DATETIME_FORMATTER.format(new Date(timestamp));
     }
 
     /**
      * Gets the string that says how long the build took to run.
      */
-    public String getDurationString() {
+    public @Nonnull String getDurationString() {
         if(isBuilding())
             return Messages.Run_InProgressDuration(
                     Util.getTimeSpanString(System.currentTimeMillis()-timestamp));
@@ -717,7 +725,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * Gets the icon color for display.
      */
-    public BallColor getIconColor() {
+    public @Nonnull BallColor getIconColor() {
         if(!isBuilding()) {
             // already built
             return getResult().color;
@@ -776,10 +784,11 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Called by {@link RunMap} to obtain a reference to this run.
+     * @return Reference to the build. Never null
      * @see jenkins.model.lazy.LazyBuildMixIn.RunMixIn#createReference
      * @since 1.556
-     */
-    protected BuildReference<RunT> createReference() {
+     */   
+    protected @Nonnull BuildReference<RunT> createReference() {
         return new BuildReference<RunT>(getId(), _this());
     }
 
@@ -798,15 +807,15 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * @see jenkins.model.lazy.LazyBuildMixIn.RunMixIn#getPreviousBuild
-     */
-    public RunT getPreviousBuild() {
+     */  
+    public @CheckForNull RunT getPreviousBuild() {
         return previousBuild;
     }
 
     /**
      * Gets the most recent {@linkplain #isBuilding() completed} build excluding 'this' Run itself.
-     */
-    public final RunT getPreviousCompletedBuild() {
+     */   
+    public final @CheckForNull RunT getPreviousCompletedBuild() {
         RunT r=getPreviousBuild();
         while (r!=null && r.isBuilding())
             r=r.getPreviousBuild();
@@ -820,8 +829,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * <p>
      * We basically follow the existing skip list, and wherever we find a non-optimal pointer, we remember them
      * in 'fixUp' and update them later.
-     */
-    public final RunT getPreviousBuildInProgress() {
+     */  
+    public final @CheckForNull RunT getPreviousBuildInProgress() {
         if(previousBuildInProgress==this)   return null;    // the most common case
 
         List<RunT> fixUp = new ArrayList<RunT>();
@@ -856,8 +865,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Returns the last build that was actually built - i.e., skipping any with Result.NOT_BUILT
-     */
-    public RunT getPreviousBuiltBuild() {
+     */ 
+    public @CheckForNull RunT getPreviousBuiltBuild() {
         RunT r=getPreviousBuild();
         // in certain situations (aborted m2 builds) r.getResult() can still be null, although it should theoretically never happen
         while( r!=null && (r.getResult() == null || r.getResult()==Result.NOT_BUILT) )
@@ -867,8 +876,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Returns the last build that didn't fail before this build.
-     */
-    public RunT getPreviousNotFailedBuild() {
+     */ 
+    public @CheckForNull RunT getPreviousNotFailedBuild() {
         RunT r=getPreviousBuild();
         while( r!=null && r.getResult()==Result.FAILURE )
             r=r.getPreviousBuild();
@@ -877,8 +886,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Returns the last failed build before this build.
-     */
-    public RunT getPreviousFailedBuild() {
+     */  
+    public @CheckForNull RunT getPreviousFailedBuild() {
         RunT r=getPreviousBuild();
         while( r!=null && r.getResult()!=Result.FAILURE )
             r=r.getPreviousBuild();
@@ -889,7 +898,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Returns the last successful build before this build.
      * @since 1.383
      */
-    public RunT getPreviousSuccessfulBuild() {
+    public @CheckForNull RunT getPreviousSuccessfulBuild() {
         RunT r=getPreviousBuild();
         while( r!=null && r.getResult()!=Result.SUCCESS )
             r=r.getPreviousBuild();
@@ -905,8 +914,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      *   May be smaller than 'numberOfBuilds' or even empty
      *   if not enough builds satisfying the threshold have been found. Never null.
      * @since 1.383
-     */
-    public List<RunT> getPreviousBuildsOverThreshold(int numberOfBuilds, Result threshold) {
+     */  
+    public @Nonnull List<RunT> getPreviousBuildsOverThreshold(int numberOfBuilds, @Nonnull Result threshold) {
         List<RunT> builds = new ArrayList<RunT>(numberOfBuilds);
         
         RunT r = getPreviousBuild();
@@ -923,8 +932,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * @see jenkins.model.lazy.LazyBuildMixIn.RunMixIn#getNextBuild
-     */
-    public RunT getNextBuild() {
+     */   
+    public @CheckForNull RunT getNextBuild() {
         return nextBuild;
     }
 
@@ -936,7 +945,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      */
     // I really messed this up. I'm hoping to fix this some time
     // it shouldn't have trailing '/', and instead it should have leading '/'
-    public String getUrl() {
+    public @Nonnull String getUrl() {
 
         // RUN may be accessed using permalinks, as "/lastSuccessful" or other, so try to retrieve this base URL
         // looking for "this" in the current request ancestors
@@ -962,11 +971,11 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      *      This method is only intended for the remote API clients who cannot resolve relative references.
      */
     @Exported(visibility=2,name="url")
-    public final String getAbsoluteUrl() {
+    public final @Nonnull String getAbsoluteUrl() {
         return project.getAbsoluteUrl()+getNumber()+'/';
     }
 
-    public final String getSearchUrl() {
+    public final @Nonnull String getSearchUrl() {
         return getNumber()+"/";
     }
 
@@ -974,29 +983,31 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Unique ID of this build.
      */
     @Exported
-    public String getId() {
+    public @Nonnull String getId() {
         return ID_FORMATTER.get().format(new Date(timestamp));
     }
     
     /**
-     * Get the date formatter used to convert the directory name in to a timestamp
+     * Get the date formatter used to convert the directory name in to a timestamp.
      * This is nasty exposure of private data, but needed all the time the directory
      * containing the build is used as it's timestamp.
      */
-    public static DateFormat getIDFormatter() {
+    public static @Nonnull DateFormat getIDFormatter() {
     	return ID_FORMATTER.get();
     }
-
-    public Descriptor getDescriptorByName(String className) {
+ 
+    @Override
+    public @CheckForNull Descriptor getDescriptorByName(String className) {
         return Jenkins.getInstance().getDescriptorByName(className);
     }
 
     /**
-     * Root directory of this {@link Run} on the master.
-     *
+     * Get the root directory of this {@link Run} on the master.
      * Files related to this {@link Run} should be stored below this directory.
+     * @return Root directory of this {@link Run} on the master. Never null
      */
-    public File getRootDir() {
+    @Override
+    public @Nonnull File getRootDir() {
         return new File(project.getBuildDir(),getId());
     }
 
@@ -1053,19 +1064,21 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Gets the artifacts (relative to {@link #getArtifactsDir()}.
-     */
-    @Exported
-    public List<Artifact> getArtifacts() {
+     * @return The list can be empty but never null
+     */    
+    @Exported  
+    public @Nonnull List<Artifact> getArtifacts() {
         return getArtifactsUpTo(Integer.MAX_VALUE);
     }
 
     /**
      * Gets the first N artifacts.
-     */
-    public List<Artifact> getArtifactsUpTo(int n) {
+     * @return The list can be empty but never null
+     */ 
+    public @Nonnull List<Artifact> getArtifactsUpTo(int artifactsNumber) {
         ArtifactList r = new ArtifactList();
         try {
-            addArtifacts(getArtifactManager().root(), "", "", r, null, n);
+            addArtifacts(getArtifactManager().root(), "", "", r, null, artifactsNumber);
         } catch (IOException x) {
             LOGGER.log(Level.WARNING, null, x);
         }
@@ -1074,16 +1087,17 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     }
 
     /**
-     * Returns true if this run has any artifacts.
-     *
-     * <p>
+     * Check if the {@link Run} contains artifacts.
      * The strange method name is so that we can access it from EL.
+     * @return true if this run has any artifacts
      */
     public boolean getHasArtifacts() {
         return !getArtifactsUpTo(1).isEmpty();
     }
 
-    private int addArtifacts(VirtualFile dir, String path, String pathHref, ArtifactList r, Artifact parent, int upTo) throws IOException {
+    private int addArtifacts(@Nonnull VirtualFile dir, 
+            @Nonnull String path, @Nonnull String pathHref, 
+            @Nonnull ArtifactList r, @Nonnull Artifact parent, int upTo) throws IOException {
         VirtualFile[] kids = dir.list();
         Arrays.sort(kids);
 
@@ -1267,7 +1281,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
          * @deprecated May not be meaningful with custom artifact managers. Use {@link ArtifactManager#root} plus {@link VirtualFile#child} with {@link #relativePath} instead.
          */
         @Deprecated
-        public File getFile() {
+        public @Nonnull File getFile() {
             return new File(getArtifactsDir(),relativePath);
         }
 
@@ -1308,8 +1322,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Returns the log file.
-     */
-    public File getLogFile() {
+     * @return The file may reference both uncompressed or compressed logs
+     */  
+    public @Nonnull File getLogFile() {
         File rawF = new File(getRootDir(), "log");
         if (rawF.isFile()) {
             return rawF;
@@ -1327,13 +1342,14 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * It will use a gzip-compressed log file (log.gz) if that exists.
      *
      * @throws IOException 
-     * @return an input stream from the log file, or null if none exists
+     * @return An input stream from the log file. 
+     *   If the log file does not exist, the error message will be returned to the output.
      * @since 1.349
      */
-    public InputStream getLogInputStream() throws IOException {
+    public @Nonnull InputStream getLogInputStream() throws IOException {
     	File logFile = getLogFile();
     	
-    	if (logFile != null && logFile.exists() ) {
+    	if (logFile.exists() ) {
     	    // Checking if a ".gz" file was return
     	    FileInputStream fis = new FileInputStream(logFile);
     	    if (logFile.getName().endsWith(".gz")) {
@@ -1346,8 +1362,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         String message = "No such file: " + logFile;
     	return new ByteArrayInputStream(charset != null ? message.getBytes(charset) : message.getBytes());
     }
-
-    public Reader getLogReader() throws IOException {
+   
+    public @Nonnull Reader getLogReader() throws IOException {
         if (charset==null)  return new InputStreamReader(getLogInputStream());
         else                return new InputStreamReader(getLogInputStream(),charset);
     }
@@ -1357,7 +1373,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      *
      * @since 1.349
      */
-    public void writeLogTo(long offset, XMLOutput out) throws IOException {
+    public void writeLogTo(long offset, @Nonnull XMLOutput out) throws IOException {
         try {
 			getLogText().writeHtmlTo(offset,out.asWriter());
 		} catch (IOException e) {
@@ -1378,8 +1394,10 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      *
      * If someone is still writing to the log, this method will not return until the whole log
      * file gets written out.
+     * <p/>
+     * The method does not close the {@link OutputStream}.
      */
-    public void writeWholeLogTo(OutputStream out) throws IOException, InterruptedException {
+    public void writeWholeLogTo(@Nonnull OutputStream out) throws IOException, InterruptedException {
         long pos = 0;
         AnnotatedLargeText logText;
         logText = getLogText();
@@ -1396,13 +1414,14 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Used to URL-bind {@link AnnotatedLargeText}.
-     */
-    public AnnotatedLargeText getLogText() {
+     * @return A {@link Run} log with annotations
+     */   
+    public @Nonnull AnnotatedLargeText getLogText() {
         return new AnnotatedLargeText(getLogFile(),getCharset(),!isLogUpdated(),this);
     }
 
     @Override
-    protected SearchIndexBuilder makeSearchIndex() {
+    protected @Nonnull SearchIndexBuilder makeSearchIndex() {
         SearchIndexBuilder builder = super.makeSearchIndex()
                 .add("console")
                 .add("changes");
@@ -1413,18 +1432,21 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         return builder;
     }
 
-    public Api getApi() {
+    public @Nonnull Api getApi() {
         return new Api(this);
     }
 
-    public void checkPermission(Permission p) {
+    @Override
+    public void checkPermission(@Nonnull Permission p) {
         getACL().checkPermission(p);
     }
 
-    public boolean hasPermission(Permission p) {
+    @Override
+    public boolean hasPermission(@Nonnull Permission p) {
         return getACL().hasPermission(p);
     }
 
+    @Override
     public ACL getACL() {
         // for now, don't maintain ACL per run, and do it at project level
         return getParent().getACL();
@@ -1495,14 +1517,14 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * @see CheckPoint#report()
      */
-    /*package*/ static void reportCheckpoint(CheckPoint id) {
+    /*package*/ static void reportCheckpoint(@Nonnull CheckPoint id) {
         RunnerStack.INSTANCE.peek().checkpoints.report(id);
     }
 
     /**
      * @see CheckPoint#block()
      */
-    /*package*/ static void waitForCheckpoint(CheckPoint id, @CheckForNull BuildListener listener, @CheckForNull String waiter) throws InterruptedException {
+    /*package*/ static void waitForCheckpoint(@Nonnull CheckPoint id, @CheckForNull BuildListener listener, @CheckForNull String waiter) throws InterruptedException {
         while(true) {
             Run b = RunnerStack.INSTANCE.peek().getBuild().getPreviousBuildInProgress();
             if(b==null)     return; // no pending earlier build
@@ -1543,12 +1565,12 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
             private boolean allDone;
 
-            protected synchronized void report(CheckPoint identifier) {
+            protected synchronized void report(@Nonnull CheckPoint identifier) {
                 checkpoints.add(identifier);
                 notifyAll();
             }
 
-            protected synchronized boolean waitForCheckPoint(CheckPoint identifier, @CheckForNull BuildListener listener, @CheckForNull String waiter) throws InterruptedException {
+            protected synchronized boolean waitForCheckPoint(@Nonnull CheckPoint identifier, @CheckForNull BuildListener listener, @CheckForNull String waiter) throws InterruptedException {
                 final Thread t = Thread.currentThread();
                 final String oldName = t.getName();
                 t.setName(oldName + " : waiting for " + identifier + " on " + getFullDisplayName() + " from " + waiter);
@@ -1586,7 +1608,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
          * @throws Exception
          *      exception will be recorded and the build will be considered a failure.
          */
-        public abstract Result run( BuildListener listener ) throws Exception, RunnerAbortedException;
+        public abstract @Nonnull Result run(@Nonnull BuildListener listener ) throws Exception, RunnerAbortedException;
 
         /**
          * Performs the post-build action.
@@ -1598,7 +1620,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
          * even if the build is successful, this build still won't be picked up
          * by {@link Job#getLastSuccessfulBuild()}.
          */
-        public abstract void post( BuildListener listener ) throws Exception;
+        public abstract void post(@Nonnull BuildListener listener ) throws Exception;
 
         /**
          * Performs final clean up action.
@@ -1612,11 +1634,11 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
          */
         public abstract void cleanUp(@Nonnull BuildListener listener) throws Exception;
 
-        public RunT getBuild() {
+        public @Nonnull RunT getBuild() {
             return _this();
         }
 
-        public JobT getProject() {
+        public @Nonnull JobT getProject() {
             return _this().getParent();
         }
 
@@ -1626,7 +1648,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
          *
          * @since 1.473
          */
-        public Map<Object,Object> getAttributes() {
+        public @Nonnull Map<Object,Object> getAttributes() {
             return attributes;
         }
     }
@@ -1644,11 +1666,11 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * @deprecated as of 1.467
      *      Use {@link #execute(RunExecution)}
      */
-    protected final void run(Runner job) {
+    protected final void run(@Nonnull Runner job) {
         execute(job);
     }
 
-    protected final void execute(RunExecution job) {
+    protected final void execute(@Nonnull RunExecution job) {
         if(result!=null)
             return;     // already built.
 
@@ -1792,7 +1814,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * @throws InterruptedException probably not thrown
      * @since 1.530
      */
-    public final void updateSymlinks(TaskListener listener) throws InterruptedException {
+    public final void updateSymlinks(@Nonnull TaskListener listener) throws InterruptedException {
         Util.createSymlink(getParent().getBuildDir(), getId(), String.valueOf(getNumber()), listener);
         createSymlink(listener, "lastSuccessful", PermalinkProjectAction.Permalink.LAST_SUCCESSFUL_BUILD);
         createSymlink(listener, "lastStable", PermalinkProjectAction.Permalink.LAST_STABLE_BUILD);
@@ -1804,7 +1826,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * builds, but now those are done in {@link PeepholePermalink}. So here, we simply create symlinks that
      * resolves to the symlink created by {@link PeepholePermalink}.
      */
-    private void createSymlink(TaskListener listener, String name, PermalinkProjectAction.Permalink target) throws InterruptedException {
+    private void createSymlink(@Nonnull TaskListener listener, @Nonnull String name, @Nonnull PermalinkProjectAction.Permalink target) throws InterruptedException {
         File buildDir = getParent().getBuildDir();
         File rootDir = getParent().getRootDir();
         String targetDir;
@@ -1819,7 +1841,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     /**
      * Handles a fatal build problem (exception) that occurred during the build.
      */
-    private void handleFatalBuildProblem(BuildListener listener, Throwable e) {
+    private void handleFatalBuildProblem(@Nonnull BuildListener listener, @Nonnull Throwable e) {
         if(listener!=null) {
             LOGGER.log(FINE, getDisplayName()+" failed to build",e);
 
@@ -1881,19 +1903,19 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         SaveableListener.fireOnChange(this, getDataFile());
     }
 
-    private XmlFile getDataFile() {
+    private @Nonnull XmlFile getDataFile() {
         return new XmlFile(XSTREAM,new File(getRootDir(),"build.xml"));
     }
 
     /**
      * Gets the log of the build as a string.
-     *
+     * @return Returns the log or an empty string if it has not been found
      * @deprecated since 2007-11-11.
      *     Use {@link #getLog(int)} instead as it avoids loading
      *     the whole log into memory unnecessarily.
      */
     @Deprecated
-    public String getLog() throws IOException {
+    public @Nonnull String getLog() throws IOException {
         return Util.loadFile(getLogFile(),getCharset());
     }
 
@@ -1906,7 +1928,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * @return A list of log lines.  Will have no more than maxLines elements.
      * @throws IOException If there is a problem reading the log file.
      */
-    public List<String> getLog(int maxLines) throws IOException {
+    public @Nonnull List<String> getLog(int maxLines) throws IOException {
         int lineCount = 0;
         List<String> logLines = new LinkedList<String>();
         BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(getLogFile()),getCharset()));
@@ -1938,7 +1960,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         rsp.sendRedirect2(req.getContextPath()+"/images/48x48/"+getBuildStatusUrl());
     }
 
-    public String getBuildStatusUrl() {
+    public @Nonnull String getBuildStatusUrl() {
         return getIconColor().getImage();
     }
 
@@ -1959,7 +1981,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Gets an object which represents the single line summary of the status of this build
      * (especially in comparison with the previous build.)
      */
-    public Summary getBuildStatusSummary() {
+    public @Nonnull Summary getBuildStatusSummary() {
         if (isBuilding()) {
             return new Summary(false, Messages.Run_Summary_Unknown());
         }
@@ -2002,7 +2024,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * @param worseOverride override the 'worse' parameter to this value.
      *   May be null in which case 'worse' is calculated based on the number of failed tests.
      */
-    private Summary determineDetailedUnstableSummary(Boolean worseOverride) {
+    private @Nonnull Summary determineDetailedUnstableSummary(Boolean worseOverride) {
         if(((Run)this) instanceof AbstractBuild) {
             AbstractTestResultAction trN = ((AbstractBuild)(Run)this).getTestResultAction();
             Run prev = getPreviousBuild();
@@ -2035,8 +2057,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     /**
      * Serves the artifacts.
+     * @throws AccessDeniedException Access denied
      */
-    public DirectoryBrowserSupport doArtifact() {
+    public @Nonnull DirectoryBrowserSupport doArtifact() {
         if(Functions.isArtifactsPermissionEnabled()) {
           checkPermission(ARTIFACTS);
         }
@@ -2231,7 +2254,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Builds up the environment variable map that's sufficient to identify a process
      * as ours. This is used to kill run-away processes via {@link ProcessTree#killAll(Map)}.
      */
-    public final EnvVars getCharacteristicEnvVars() {
+    public @Nonnull final EnvVars getCharacteristicEnvVars() {
         EnvVars env = getParent().getCharacteristicEnvVars();
         env.put("BUILD_NUMBER",String.valueOf(number));
         env.put("BUILD_ID",getId());
@@ -2239,11 +2262,11 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         return env;
     }
 
-    public String getExternalizableId() {
+    public @Nonnull String getExternalizableId() {
         return project.getFullName() + "#" + getNumber();
     }
 
-    public static Run<?,?> fromExternalizableId(String id) {
+    public @Nonnull static Run<?,?> fromExternalizableId(String id) {
         int hash = id.lastIndexOf('#');
         if (hash <= 0) {
             throw new IllegalArgumentException("Invalid id");
@@ -2272,7 +2295,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
     }
 
     @RequirePOST
-    public HttpResponse doConfigSubmit( StaplerRequest req ) throws IOException, ServletException, FormException {
+    public @Nonnull HttpResponse doConfigSubmit( StaplerRequest req ) throws IOException, ServletException, FormException {
         checkPermission(UPDATE);
         BulkChange bc = new BulkChange(this);
         try {
@@ -2308,7 +2331,7 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Sort by date. Newer ones first. 
      */
     public static final Comparator<Run> ORDER_BY_DATE = new Comparator<Run>() {
-        public int compare(Run lhs, Run rhs) {
+        public int compare(@Nonnull Run lhs, @Nonnull Run rhs) {
             long lt = lhs.getTimeInMillis();
             long rt = rhs.getTimeInMillis();
             if(lt>rt)   return -1;
@@ -2341,10 +2364,10 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * {@link BuildBadgeAction} that shows the logs are being kept.
      */
     public final class KeepLogBuildBadge implements BuildBadgeAction {
-        public String getIconFileName() { return null; }
-        public String getDisplayName() { return null; }
-        public String getUrlName() { return null; }
-        public String getWhyKeepLog() { return Run.this.getWhyKeepLog(); }
+        public @CheckForNull String getIconFileName() { return null; }
+        public @CheckForNull String getDisplayName() { return null; }
+        public @CheckForNull String getUrlName() { return null; }
+        public @CheckForNull String getWhyKeepLog() { return Run.this.getWhyKeepLog(); }
     }
 
     public static final PermissionGroup PERMISSIONS = new PermissionGroup(Run.class,Messages._Run_Permissions_Title());
@@ -2384,8 +2407,8 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     @Override
     public Object getDynamic(String token, StaplerRequest req, StaplerResponse rsp) {
-        Object result = super.getDynamic(token, req, rsp);
-        if (result == null){
+        Object returnedResult = super.getDynamic(token, req, rsp);
+        if (returnedResult == null){
             //check transient actions too
             for(Action action: getTransientActions()){
                 String urlName = action.getUrlName();
@@ -2399,9 +2422,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
             // Next/Previous Build links on an action page (like /job/Abc/123/testReport)
             // will also point to same action (/job/Abc/124/testReport), but other builds
             // may not have the action.. tell browsers to redirect up to the build page.
-            result = new RedirectUp();
+            returnedResult = new RedirectUp();
         }
-        return result;
+        return returnedResult;
     }
 
     public static class RedirectUp {
diff --git a/core/src/main/java/hudson/node_monitors/DiskSpaceMonitor.java b/core/src/main/java/hudson/node_monitors/DiskSpaceMonitor.java
index 705675f0357bfd8baa29de59a8843d2fec287dc7..9f185b589117b65b7597f6a5effa3ccbe3398ba2 100644
--- a/core/src/main/java/hudson/node_monitors/DiskSpaceMonitor.java
+++ b/core/src/main/java/hudson/node_monitors/DiskSpaceMonitor.java
@@ -26,6 +26,7 @@ package hudson.node_monitors;
 import hudson.Extension;
 import hudson.FilePath;
 import hudson.model.Computer;
+import hudson.model.Node;
 import hudson.remoting.Callable;
 import jenkins.model.Jenkins;
 import hudson.node_monitors.DiskSpaceMonitorDescriptor.DiskSpace;
@@ -66,7 +67,10 @@ public class DiskSpaceMonitor extends AbstractDiskSpaceMonitor {
 
         @Override
         protected Callable<DiskSpace, IOException> createCallable(Computer c) {
-            FilePath p = c.getNode().getRootPath();
+            Node node = c.getNode();
+            if (node == null) return null;
+            
+            FilePath p = node.getRootPath();
             if(p==null) return null;
 
             return p.asCallableWith(new GetUsableSpace());
diff --git a/core/src/main/java/hudson/node_monitors/TemporarySpaceMonitor.java b/core/src/main/java/hudson/node_monitors/TemporarySpaceMonitor.java
index c43d63a5093e81af583264b5f20fd339f53a3252..e42951ff12cd1263f7d029a3e4293248bd3e866f 100644
--- a/core/src/main/java/hudson/node_monitors/TemporarySpaceMonitor.java
+++ b/core/src/main/java/hudson/node_monitors/TemporarySpaceMonitor.java
@@ -27,6 +27,7 @@ import hudson.Extension;
 import hudson.FilePath;
 import hudson.FilePath.FileCallable;
 import hudson.model.Computer;
+import hudson.model.Node;
 import hudson.remoting.Callable;
 import jenkins.model.Jenkins;
 import hudson.node_monitors.DiskSpaceMonitorDescriptor.DiskSpace;
@@ -67,7 +68,10 @@ public class TemporarySpaceMonitor extends AbstractDiskSpaceMonitor {
 
         @Override
         protected Callable<DiskSpace,IOException> createCallable(Computer c) {
-            FilePath p = c.getNode().getRootPath();
+            Node node = c.getNode();
+            if (node == null) return null;
+            
+            FilePath p = node.getRootPath();
             if(p==null) return null;
 
             return p.asCallableWith(new GetTempSpace());
diff --git a/core/src/main/java/hudson/security/ACL.java b/core/src/main/java/hudson/security/ACL.java
index 132344fc525cdd4fcc289c0ef3a1c2f07fbccbc6..d13b53ec969f7ede1a2583b3c62d7916929203fd 100644
--- a/core/src/main/java/hudson/security/ACL.java
+++ b/core/src/main/java/hudson/security/ACL.java
@@ -23,6 +23,7 @@
  */
 package hudson.security;
 
+import javax.annotation.Nonnull;
 import jenkins.security.NonSerializableSecurityContext;
 import jenkins.model.Jenkins;
 import org.acegisecurity.AccessDeniedException;
@@ -48,7 +49,7 @@ public abstract class ACL {
      * @throws AccessDeniedException
      *      if the user doesn't have the permission.
      */
-    public final void checkPermission(Permission p) {
+    public final void checkPermission(@Nonnull Permission p) {
         Authentication a = Jenkins.getAuthentication();
         if(!hasPermission(a,p))
             throw new AccessDeniedException2(a,p);
@@ -60,7 +61,7 @@ public abstract class ACL {
      * @return false
      *      if the user doesn't have the permission.
      */
-    public final boolean hasPermission(Permission p) {
+    public final boolean hasPermission(@Nonnull Permission p) {
         return hasPermission(Jenkins.getAuthentication(),p);
     }
 
@@ -71,7 +72,7 @@ public abstract class ACL {
      * Note that {@link #SYSTEM} can be passed in as the authentication parameter,
      * in which case you should probably just assume it has every permission.
      */
-    public abstract boolean hasPermission(Authentication a, Permission permission);
+    public abstract boolean hasPermission(@Nonnull Authentication a, @Nonnull Permission permission);
 
     //
     // Sid constants
@@ -124,7 +125,7 @@ public abstract class ACL {
      * because the same {@link SecurityContext} object is reused for all the concurrent requests from the same session.
      * @since 1.462
      */
-    public static SecurityContext impersonate(Authentication auth) {
+    public static @Nonnull SecurityContext impersonate(@Nonnull Authentication auth) {
         SecurityContext old = SecurityContextHolder.getContext();
         SecurityContextHolder.setContext(new NonSerializableSecurityContext(auth));
         return old;
@@ -136,7 +137,7 @@ public abstract class ACL {
      * @param body an action to run with this alternate authentication in effect
      * @since 1.509
      */
-    public static void impersonate(Authentication auth, Runnable body) {
+    public static void impersonate(@Nonnull Authentication auth, @Nonnull Runnable body) {
         SecurityContext old = impersonate(auth);
         try {
             body.run();
diff --git a/core/src/main/java/hudson/security/AccessControlled.java b/core/src/main/java/hudson/security/AccessControlled.java
index 5bed4a28dc3d0a70695121aee180ea5afc5f5347..0b3e81adde90c7664ed7927b9fc017f6a281f87a 100644
--- a/core/src/main/java/hudson/security/AccessControlled.java
+++ b/core/src/main/java/hudson/security/AccessControlled.java
@@ -23,6 +23,7 @@
  */
 package hudson.security;
 
+import javax.annotation.Nonnull;
 import org.acegisecurity.AccessDeniedException;
 
 /**
@@ -36,16 +37,16 @@ public interface AccessControlled {
      *
      * @return never null.
      */
-    ACL getACL();
+    @Nonnull ACL getACL();
 
     /**
      * Convenient short-cut for {@code getACL().checkPermission(permission)}
      */
-    void checkPermission(Permission permission) throws AccessDeniedException;
+    void checkPermission(@Nonnull Permission permission) throws AccessDeniedException;
 
     /**
      * Convenient short-cut for {@code getACL().hasPermission(permission)}
      */
-    boolean hasPermission(Permission permission);
+    boolean hasPermission(@Nonnull Permission permission);
 
 }
diff --git a/core/src/main/java/hudson/security/AuthorizationStrategy.java b/core/src/main/java/hudson/security/AuthorizationStrategy.java
index b110647fb5a367339e1d16e101fc6fa7006f1627..da7d7348fd5d42197924018d29efa18ada5ca6dd 100644
--- a/core/src/main/java/hudson/security/AuthorizationStrategy.java
+++ b/core/src/main/java/hudson/security/AuthorizationStrategy.java
@@ -33,6 +33,7 @@ import hudson.util.DescriptorList;
 import java.io.Serializable;
 import java.util.Collection;
 import java.util.Collections;
+import javax.annotation.Nonnull;
 
 import jenkins.model.Jenkins;
 import net.sf.json.JSONObject;
@@ -68,18 +69,18 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      * <p>
      * IOW, this ACL will have the ultimate say on the access control.
      */
-    public abstract ACL getRootACL();
+    public abstract @Nonnull ACL getRootACL();
 
     /**
      * @deprecated since 1.277
      *      Override {@link #getACL(Job)} instead.
      */
     @Deprecated
-    public ACL getACL(AbstractProject<?,?> project) {
+    public @Nonnull ACL getACL(@Nonnull AbstractProject<?,?> project) {
     	return getACL((Job)project);
     }
 
-    public ACL getACL(Job<?,?> project) {
+    public @Nonnull ACL getACL(@Nonnull Job<?,?> project) {
     	return getRootACL();
     }
 
@@ -93,7 +94,7 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      *
      * @since 1.220
      */
-    public ACL getACL(final View item) {
+    public @Nonnull ACL getACL(final @Nonnull View item) {
         return new ACL() {
             @Override
             public boolean hasPermission(Authentication a, Permission permission) {
@@ -118,7 +119,7 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      *
      * @since 1.220
      */
-    public ACL getACL(AbstractItem item) {
+    public @Nonnull ACL getACL(@Nonnull AbstractItem item) {
         return getRootACL();
     }
 
@@ -131,7 +132,7 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      *
      * @since 1.221
      */
-    public ACL getACL(User user) {
+    public @Nonnull ACL getACL(@Nonnull User user) {
         return getRootACL();
     }
 
@@ -144,7 +145,7 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      *
      * @since 1.220
      */
-    public ACL getACL(Computer computer) {
+    public @Nonnull ACL getACL(@Nonnull Computer computer) {
         return getACL(computer.getNode());
     }
 
@@ -157,11 +158,11 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      *
      * @since 1.252
      */
-    public ACL getACL(Cloud cloud) {
+    public @Nonnull ACL getACL(@Nonnull Cloud cloud) {
         return getRootACL();
     }
 
-    public ACL getACL(Node node) {
+    public @Nonnull ACL getACL(@Nonnull Node node) {
         return getRootACL();
     }
 
@@ -179,12 +180,12 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      * @return
      *      never null.
      */
-    public abstract Collection<String> getGroups();
+    public abstract @Nonnull Collection<String> getGroups();
 
     /**
      * Returns all the registered {@link AuthorizationStrategy} descriptors.
      */
-    public static DescriptorExtensionList<AuthorizationStrategy,Descriptor<AuthorizationStrategy>> all() {
+    public static @Nonnull DescriptorExtensionList<AuthorizationStrategy,Descriptor<AuthorizationStrategy>> all() {
         return Jenkins.getInstance().<AuthorizationStrategy,Descriptor<AuthorizationStrategy>>getDescriptorList(AuthorizationStrategy.class);
     }
 
@@ -214,15 +215,17 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
         }
 
         @Override
-        public ACL getRootACL() {
+        public @Nonnull ACL getRootACL() {
             return UNSECURED_ACL;
         }
 
-        public Collection<String> getGroups() {
+        @Override
+        public @Nonnull Collection<String> getGroups() {
             return Collections.emptySet();
         }
 
         private static final ACL UNSECURED_ACL = new ACL() {
+            @Override
             public boolean hasPermission(Authentication a, Permission permission) {
                 return true;
             }
@@ -230,12 +233,13 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
 
         @Extension
         public static final class DescriptorImpl extends Descriptor<AuthorizationStrategy> {
+            @Override
             public String getDisplayName() {
                 return Messages.AuthorizationStrategy_DisplayName();
             }
 
             @Override
-            public AuthorizationStrategy newInstance(StaplerRequest req, JSONObject formData) throws FormException {
+            public @Nonnull AuthorizationStrategy newInstance(StaplerRequest req, JSONObject formData) throws FormException {
                 return UNSECURED;
             }
 
diff --git a/core/src/main/java/hudson/security/Permission.java b/core/src/main/java/hudson/security/Permission.java
index f9b6bd4a0fd6db901f3ec555729c07e0dfe00f43..20c43b09803c885f01c7b82e28e1b55810d9e989 100644
--- a/core/src/main/java/hudson/security/Permission.java
+++ b/core/src/main/java/hudson/security/Permission.java
@@ -34,6 +34,7 @@ import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CopyOnWriteArrayList;
 import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
 
 import org.jvnet.localizer.Localizable;
 
@@ -58,14 +59,14 @@ public final class Permission {
          */
         // break eclipse compilation 
         //Override
-        public int compare(Permission one, Permission two) {
+        public int compare(@Nonnull Permission one, @Nonnull Permission two) {
             return one.getId().compareTo(two.getId());
         }
     };
 
-    public final Class owner;
+    public final @Nonnull Class owner;
 
-    public final PermissionGroup group;
+    public final @Nonnull PermissionGroup group;
 
     /**
      * Human readable ID of the permission.
@@ -76,7 +77,7 @@ public final class Permission {
      * <p>
      * The expected naming convention is something like "BrowseWorkspace".
      */
-    public final String name;
+    public final @Nonnull String name;
 
     /**
      * Human-readable description of this permission.
@@ -86,7 +87,7 @@ public final class Permission {
      * <p>
      * If null, there will be no description text.
      */
-    public final Localizable description;
+    public final @CheckForNull Localizable description;
 
     /**
      * Bundled {@link Permission} that also implies this permission.
@@ -101,7 +102,7 @@ public final class Permission {
      * such broad permission bundle is good enough, and those few
      * that need finer control can do so.
      */
-    public final Permission impliedBy;
+    public final @CheckForNull Permission impliedBy;
 
     /**
      * Whether this permission is available for use.
@@ -118,7 +119,7 @@ public final class Permission {
     /**
      * Scopes that this permission is directly contained by.
      */
-    private final Set<PermissionScope> scopes;
+    private final @Nonnull Set<PermissionScope> scopes;
 
     /**
      * Defines a new permission.
@@ -144,7 +145,9 @@ public final class Permission {
      * @param impliedBy
      *      See {@link #impliedBy}.
      */
-    public Permission(PermissionGroup group, String name, Localizable description, Permission impliedBy, boolean enable, PermissionScope[] scopes) {
+    public Permission(@Nonnull PermissionGroup group, @Nonnull String name, 
+            @CheckForNull Localizable description, @CheckForNull Permission impliedBy, boolean enable, 
+            @Nonnull PermissionScope[] scopes) {
         if(!JSONUtils.isJavaIdentifier(name))
             throw new IllegalArgumentException(name+" is not a Java identifier");
         this.owner = group.owner;
@@ -159,7 +162,8 @@ public final class Permission {
         ALL.add(this);
     }
 
-    public Permission(PermissionGroup group, String name, Localizable description, Permission impliedBy, PermissionScope scope) {
+    public Permission(@Nonnull PermissionGroup group, @Nonnull String name, 
+            @CheckForNull Localizable description, @CheckForNull Permission impliedBy, @Nonnull PermissionScope scope) {
         this(group,name,description,impliedBy,true,new PermissionScope[]{scope});
         assert scope!=null;
     }
@@ -168,7 +172,7 @@ public final class Permission {
      * @deprecated as of 1.421
      *      Use {@link #Permission(PermissionGroup, String, Localizable, Permission, boolean, PermissionScope[])}
      */
-    public Permission(PermissionGroup group, String name, Localizable description, Permission impliedBy, boolean enable) {
+    public Permission(@Nonnull PermissionGroup group, @Nonnull String name, @CheckForNull Localizable description, @CheckForNull Permission impliedBy, boolean enable) {
         this(group,name,description,impliedBy,enable,new PermissionScope[]{PermissionScope.JENKINS});
     }
 
@@ -176,7 +180,7 @@ public final class Permission {
      * @deprecated as of 1.421
      *      Use {@link #Permission(PermissionGroup, String, Localizable, Permission, PermissionScope)}
      */
-    public Permission(PermissionGroup group, String name, Localizable description, Permission impliedBy) {
+    public Permission(@Nonnull PermissionGroup group, @Nonnull String name, @CheckForNull Localizable description, @CheckForNull Permission impliedBy) {
         this(group, name, description, impliedBy, PermissionScope.JENKINS);
     }
 
@@ -184,18 +188,18 @@ public final class Permission {
      * @deprecated since 1.257.
      *      Use {@link #Permission(PermissionGroup, String, Localizable, Permission)}
      */
-    public Permission(PermissionGroup group, String name, Permission impliedBy) {
+    public Permission(@Nonnull PermissionGroup group, @Nonnull String name, @CheckForNull Permission impliedBy) {
         this(group,name,null,impliedBy);
     }
 
-    private Permission(PermissionGroup group, String name) {
+    private Permission(@Nonnull PermissionGroup group, @Nonnull String name) {
         this(group,name,null,null);
     }
 
     /**
      * Checks if this permission is contained in the specified scope, (either directly or indirectly.)
      */
-    public boolean isContainedBy(PermissionScope s) {
+    public boolean isContainedBy(@Nonnull PermissionScope s) {
         for (PermissionScope c : scopes) {
             if (c.isContainedBy(s))
                 return true;
@@ -210,10 +214,10 @@ public final class Permission {
      *
      * <p>
      * This string representation is suitable for persistence.
-     *
+     * @return ID with the following format: <i>permissionClass.permissionName</i> 
      * @see #fromId(String)
      */
-    public String getId() {
+    public @Nonnull String getId() {
         return owner.getName()+'.'+name;
     }
 
@@ -224,7 +228,7 @@ public final class Permission {
      *      null if the conversion failed.
      * @see #getId()
      */
-    public static @CheckForNull Permission fromId(String id) {
+    public static @CheckForNull Permission fromId(@Nonnull String id) {
         int idx = id.lastIndexOf('.');
         if(idx<0)   return null;
 
@@ -257,7 +261,7 @@ public final class Permission {
      * @return
      *      always non-null. Read-only.
      */
-    public static List<Permission> getAll() {
+    public static @Nonnull List<Permission> getAll() {
         return ALL_VIEW;
     }
 
diff --git a/core/src/main/java/hudson/slaves/AbstractCloudComputer.java b/core/src/main/java/hudson/slaves/AbstractCloudComputer.java
index 2719f438c0d84a9b5205d484d44e3c61e3b429b9..32acc2030a2bcc56ccc5ed4a93ce4b4e09bb27f9 100644
--- a/core/src/main/java/hudson/slaves/AbstractCloudComputer.java
+++ b/core/src/main/java/hudson/slaves/AbstractCloudComputer.java
@@ -29,6 +29,7 @@ import org.kohsuke.stapler.HttpResponse;
 import org.kohsuke.stapler.HttpResponses;
 
 import java.io.IOException;
+import javax.annotation.CheckForNull;
 
 /**
  * Partial implementation of {@link Computer} to be used in conjunction with
@@ -42,6 +43,7 @@ public class AbstractCloudComputer<T extends AbstractCloudSlave> extends SlaveCo
         super(slave);
     }
 
+    @CheckForNull
     @Override
     public T getNode() {
         return (T) super.getNode();
@@ -54,7 +56,10 @@ public class AbstractCloudComputer<T extends AbstractCloudSlave> extends SlaveCo
     public HttpResponse doDoDelete() throws IOException {
         checkPermission(DELETE);
         try {
-            getNode().terminate();
+            T node = getNode();
+            if (node != null) { // No need to terminate nodes again
+                node.terminate();
+            }
             return new HttpRedirect("..");
         } catch (InterruptedException e) {
             return HttpResponses.error(500,e);
diff --git a/core/src/main/java/hudson/slaves/CloudRetentionStrategy.java b/core/src/main/java/hudson/slaves/CloudRetentionStrategy.java
index d15180fa95deca804ee52a374ca3cfb96ce598b0..562a39331ee47b2dc4a5fe760a6f2ef3d0ceaf85 100644
--- a/core/src/main/java/hudson/slaves/CloudRetentionStrategy.java
+++ b/core/src/main/java/hudson/slaves/CloudRetentionStrategy.java
@@ -23,10 +23,12 @@
  */
 package hudson.slaves;
 
+import hudson.model.Node;
 import java.io.IOException;
 import java.util.logging.Logger;
 
 import static hudson.util.TimeUnit2.*;
+import java.util.logging.Level;
 import static java.util.logging.Level.*;
 
 /**
@@ -43,13 +45,15 @@ public class CloudRetentionStrategy extends RetentionStrategy<AbstractCloudCompu
         this.idleMinutes = idleMinutes;
     }
 
+    @Override
     public synchronized long check(AbstractCloudComputer c) {
-        if (c.isIdle() && !disabled) {
+        AbstractCloudSlave computerNode = c.getNode();
+        if (c.isIdle() && !disabled && computerNode != null) {
             final long idleMilliseconds = System.currentTimeMillis() - c.getIdleStartMilliseconds();
             if (idleMilliseconds > MINUTES.toMillis(idleMinutes)) {
-                LOGGER.info("Disconnecting "+c.getName());
+                LOGGER.log(Level.INFO, "Disconnecting {0}",c.getName());
                 try {
-                    c.getNode().terminate();
+                    computerNode.terminate();
                 } catch (InterruptedException e) {
                     LOGGER.log(WARNING,"Failed to terminate "+c.getName(),e);
                 } catch (IOException e) {
diff --git a/core/src/main/java/hudson/slaves/CommandLauncher.java b/core/src/main/java/hudson/slaves/CommandLauncher.java
index 8c86abccad3600a79c8bf94105b12f19a8e03bd1..8d08f9b39c3a97ee010b4ce470773cf9e7132878 100644
--- a/core/src/main/java/hudson/slaves/CommandLauncher.java
+++ b/core/src/main/java/hudson/slaves/CommandLauncher.java
@@ -23,10 +23,12 @@
  */
 package hudson.slaves;
 
+import hudson.AbortException;
 import hudson.EnvVars;
 import hudson.Util;
 import hudson.Extension;
 import hudson.model.Descriptor;
+import hudson.model.Slave;
 import jenkins.model.Jenkins;
 import hudson.model.TaskListener;
 import hudson.remoting.Channel;
@@ -87,6 +89,11 @@ public class CommandLauncher extends ComputerLauncher {
         EnvVars _cookie = null;
         Process _proc = null;
         try {
+            Slave node = computer.getNode();
+            if (node == null) { 
+                throw new AbortException("Cannot launch commands on deleted nodes");
+            }
+            
             listener.getLogger().println(hudson.model.Messages.Slave_Launching(getTimestamp()));
             if(getCommand().trim().length()==0) {
                 listener.getLogger().println(Messages.CommandLauncher_NoLaunchCommand());
@@ -96,8 +103,8 @@ public class CommandLauncher extends ComputerLauncher {
 
             ProcessBuilder pb = new ProcessBuilder(Util.tokenize(getCommand()));
             final EnvVars cookie = _cookie = EnvVars.createCookie();
-            pb.environment().putAll(cookie);
-            pb.environment().put("WORKSPACE", computer.getNode().getRemoteFS()); //path for local slave log
+            pb.environment().putAll(cookie);      
+            pb.environment().put("WORKSPACE", node.getRemoteFS()); //path for local slave log
 
             {// system defined variables
                 String rootUrl = Jenkins.getInstance().getRootUrl();
diff --git a/core/src/main/java/hudson/slaves/NodeSpecific.java b/core/src/main/java/hudson/slaves/NodeSpecific.java
index d585ab3d04a838c2798fcd6cf42edcc038e27dfa..59ee2ca217dfaeb99db40d7c69bbefbf58f46f00 100644
--- a/core/src/main/java/hudson/slaves/NodeSpecific.java
+++ b/core/src/main/java/hudson/slaves/NodeSpecific.java
@@ -24,6 +24,7 @@
 
 package hudson.slaves;
 
+import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.model.Node;
 import hudson.model.EnvironmentSpecific;
 import hudson.model.TaskListener;
@@ -44,5 +45,5 @@ public interface NodeSpecific<T extends NodeSpecific<T>> {
     /**
      * Returns a specialized copy of T for functioning in the given node.
      */
-    T forNode(Node node, TaskListener log) throws IOException, InterruptedException;
+    T forNode(@NonNull Node node, TaskListener log) throws IOException, InterruptedException;
 }
diff --git a/core/src/main/java/hudson/slaves/RetentionStrategy.java b/core/src/main/java/hudson/slaves/RetentionStrategy.java
index bb595954a462d8595b729e98a29cdcc1856fcfe4..95cb99b375b1b6da3b44e9878034d4755254c58d 100644
--- a/core/src/main/java/hudson/slaves/RetentionStrategy.java
+++ b/core/src/main/java/hudson/slaves/RetentionStrategy.java
@@ -193,6 +193,7 @@ public abstract class RetentionStrategy<T extends Computer> extends AbstractDesc
             return idleDelay;
         }
 
+        @Override
         public synchronized long check(SlaveComputer c) {
             if (c.isOffline() && c.isLaunchSupported()) {
                 final HashMap<Computer, Integer> availableComputers = new HashMap<Computer, Integer>();
@@ -211,7 +212,8 @@ public abstract class RetentionStrategy<T extends Computer> extends AbstractDesc
                     // assume the answer is no until we can find such an executor
                     boolean needExecutor = true;
                     for (Computer o : Collections.unmodifiableSet(availableComputers.keySet())) {
-                        if (o.getNode().canTake(item) == null) {
+                        Node otherNode = o.getNode();
+                        if (otherNode != null && otherNode.canTake(item) == null) {
                             needExecutor = false;
                             final int availableExecutors = availableComputers.remove(o);
                             if (availableExecutors > 1) {
@@ -224,7 +226,8 @@ public abstract class RetentionStrategy<T extends Computer> extends AbstractDesc
                     }
 
                     // this 'item' cannot be built by any of the existing idle nodes, but it can be built by 'c'
-                    if (needExecutor && c.getNode().canTake(item) == null) {
+                    Node checkedNode = c.getNode();
+                    if (needExecutor && checkedNode != null && checkedNode.canTake(item) == null) {
                         demandMilliseconds = System.currentTimeMillis() - item.buildableStartMilliseconds;
                         needComputer = demandMilliseconds > inDemandDelay * 1000 * 60 /*MINS->MILLIS*/;
                         break;
@@ -251,6 +254,7 @@ public abstract class RetentionStrategy<T extends Computer> extends AbstractDesc
 
         @Extension
         public static class DescriptorImpl extends Descriptor<RetentionStrategy<?>> {
+            @Override
             public String getDisplayName() {
                 return Messages.RetentionStrategy_Demand_displayName();
             }
diff --git a/core/src/main/java/hudson/slaves/SlaveComputer.java b/core/src/main/java/hudson/slaves/SlaveComputer.java
index 3a73b99829f9569df3bed17d48c4bd12cd5bd36e..700bf44d5943a26397a188db8f22aa2c7b353912 100644
--- a/core/src/main/java/hudson/slaves/SlaveComputer.java
+++ b/core/src/main/java/hudson/slaves/SlaveComputer.java
@@ -78,8 +78,11 @@ import java.util.logging.Level;
 import java.util.logging.LogRecord;
 import java.util.logging.Logger;
 
+import javax.annotation.CheckForNull;
+import jenkins.model.Jenkins;
 import static hudson.slaves.SlaveComputer.LogHolder.*;
 
+
 /**
  * {@link Computer} for {@link Slave}s.
  *
@@ -168,6 +171,7 @@ public class SlaveComputer extends Computer {
         return isUnix;
     }
 
+    @CheckForNull
     @Override
     public Slave getNode() {
         Node node = super.getNode();
@@ -418,7 +422,7 @@ public class SlaveComputer extends Computer {
     }
 
     /**
-     * Sets up the connection through an exsting channel.
+     * Sets up the connection through an existing channel.
      *
      * @since 1.444
      */
@@ -454,10 +458,15 @@ public class SlaveComputer extends Computer {
 
         String defaultCharsetName = channel.call(new DetectDefaultCharset());
 
-        String remoteFs = getNode().getRemoteFS();
+        Slave node = getNode();
+        if (node == null) { // Node has been disabled/removed during the connection
+            throw new IOException("Node "+nodeName+" has been deleted during the channel setup");
+        }
+        
+        String remoteFs = node.getRemoteFS();
         if(_isUnix && !remoteFs.contains("/") && remoteFs.contains("\\"))
             log.println("WARNING: "+remoteFs+" looks suspiciously like Windows path. Maybe you meant "+remoteFs.replace('\\','/')+"?");
-        FilePath root = new FilePath(channel,getNode().getRemoteFS());
+        FilePath root = new FilePath(channel,remoteFs);
 
         // reference counting problem is known to happen, such as JENKINS-9017, and so as a preventive measure
         // we pin the base classloader so that it'll never get GCed. When this classloader gets released,
diff --git a/core/src/main/java/hudson/tasks/BuildTrigger.java b/core/src/main/java/hudson/tasks/BuildTrigger.java
index 7f4bfbeed4198d774d436c59d9a58a4334a1b7ce..40533373fd736bff524f1abd0058ac432f879805 100644
--- a/core/src/main/java/hudson/tasks/BuildTrigger.java
+++ b/core/src/main/java/hudson/tasks/BuildTrigger.java
@@ -247,11 +247,9 @@ public class BuildTrigger extends Recorder implements DependencyDeclarer {
                         logger.println(Messages.BuildTrigger_Disabled(ModelHyperlinkNote.encodeTo(p)));
                         continue;
                     }
-                    // this is not completely accurate, as a new build might be triggered
-                    // between these calls
                     boolean scheduled = p.scheduleBuild(p.getQuietPeriod(), new UpstreamCause((Run)build), buildActions.toArray(new Action[buildActions.size()]));
                     if (Jenkins.getInstance().getItemByFullName(p.getFullName()) == p) {
-                        String name = ModelHyperlinkNote.encodeTo(p) + " #" + p.getNextBuildNumber();
+                        String name = ModelHyperlinkNote.encodeTo(p);
                         if (scheduled) {
                             logger.println(Messages.BuildTrigger_Triggering(name));
                         } else {
diff --git a/core/src/main/java/hudson/tools/ToolInstallation.java b/core/src/main/java/hudson/tools/ToolInstallation.java
index 890d13e69bdaa2b1c4d0c9ad9d4971acdd087697..0ba5dd730c871b21732708586b6616654463cbeb 100644
--- a/core/src/main/java/hudson/tools/ToolInstallation.java
+++ b/core/src/main/java/hudson/tools/ToolInstallation.java
@@ -41,6 +41,7 @@ import java.util.List;
 import com.thoughtworks.xstream.annotations.XStreamSerializable;
 import com.thoughtworks.xstream.converters.UnmarshallingContext;
 import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
 import jenkins.model.Jenkins;
 
 /**
@@ -163,7 +164,7 @@ public abstract class ToolInstallation extends AbstractDescribableImpl<ToolInsta
      * @see EnvironmentSpecific
      * @since 1.460
      */
-    public ToolInstallation translate(Node node, EnvVars envs, TaskListener listener) throws IOException, InterruptedException {
+    public ToolInstallation translate(@Nonnull Node node, EnvVars envs, TaskListener listener) throws IOException, InterruptedException {
         ToolInstallation t = this;
         if (t instanceof NodeSpecific) {
             NodeSpecific n = (NodeSpecific) t;
diff --git a/core/src/main/java/jenkins/model/PeepholePermalink.java b/core/src/main/java/jenkins/model/PeepholePermalink.java
index 8e92e547d434d184e5b2a22d4e94dbeb7b1ee76b..3804b470afadc62a913ccec80e3bf0a81650ca9b 100644
--- a/core/src/main/java/jenkins/model/PeepholePermalink.java
+++ b/core/src/main/java/jenkins/model/PeepholePermalink.java
@@ -210,10 +210,11 @@ public abstract class PeepholePermalink extends Permalink implements Predicate<R
         public void onDeleted(Run run) {
             Job<?, ?> j = run.getParent();
             for (PeepholePermalink pp : Util.filter(j.getPermalinks(), PeepholePermalink.class)) {
-                if (pp.apply(run)) {
-                    if (pp.resolve(j)==run) {
-                        pp.updateCache(j,pp.find(run.getPreviousBuild()));
-                    }
+                if (pp.resolve(j)==run) {
+                    Run<?,?> r = pp.find(run.getPreviousBuild());
+                    if (LOGGER.isLoggable(Level.FINE))
+                        LOGGER.fine("Updating "+pp.getPermalinkFile(j).getName()+" permalink from deleted "+run.getNumber()+" to "+(r == null ? -1 : r.getNumber()));
+                    pp.updateCache(j,r);
                 }
             }
         }
@@ -227,8 +228,11 @@ public abstract class PeepholePermalink extends Permalink implements Predicate<R
             for (PeepholePermalink pp : Util.filter(j.getPermalinks(), PeepholePermalink.class)) {
                 if (pp.apply(run)) {
                     Run<?, ?> cur = pp.resolve(j);
-                    if (cur==null || cur.getNumber()<run.getNumber())
+                    if (cur==null || cur.getNumber()<run.getNumber()) {
+                        if (LOGGER.isLoggable(Level.FINE))
+                            LOGGER.fine("Updating "+pp.getPermalinkFile(j).getName()+" permalink to completed "+run.getNumber());
                         pp.updateCache(j,run);
+                    }
                 }
             }
         }
diff --git a/debian/debian/changelog b/debian/debian/changelog
index 3fc5042e339a29b15ad85478c2ad02c899a365e0..2df5a03194e379a3f88dca00c919ceb3ea4532d1 100644
--- a/debian/debian/changelog
+++ b/debian/debian/changelog
@@ -1,3 +1,9 @@
+jenkins (1.566) unstable; urgency=low
+
+  * See http://jenkins-ci.org/changelog for more details.
+
+ -- Kohsuke Kawaguchi <kk@kohsuke.org>  Mon, 02 Jun 2014 08:18:10 -0700
+
 jenkins (1.565) unstable; urgency=low
 
   * See http://jenkins-ci.org/changelog for more details.
diff --git a/plugins/pom.xml b/plugins/pom.xml
index 2863a3e4172dda8293accd8130542f389e141f35..3230896b79934af8ec54d5b1334e5003d0115881 100644
--- a/plugins/pom.xml
+++ b/plugins/pom.xml
@@ -11,7 +11,7 @@
   <groupId>org.jenkins-ci.plugins</groupId>
   <artifactId>plugin</artifactId>
   <name>Jenkins plugin POM</name>
-  <version>1.567-SNAPSHOT</version>
+  <version>1.568-SNAPSHOT</version>
   <packaging>pom</packaging>
 
   <!--
@@ -39,19 +39,19 @@
       <groupId>org.jenkins-ci.main</groupId>
       <artifactId>jenkins-war</artifactId>
       <type>war</type>
-      <version>1.567-SNAPSHOT</version>
+      <version>1.568-SNAPSHOT</version>
       <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>org.jenkins-ci.main</groupId>
       <artifactId>jenkins-core</artifactId>
-      <version>1.567-SNAPSHOT</version>
+      <version>1.568-SNAPSHOT</version>
       <scope>provided</scope>
     </dependency>
     <dependency>
       <groupId>org.jenkins-ci.main</groupId>
       <artifactId>jenkins-test-harness</artifactId>
-      <version>1.567-SNAPSHOT</version>
+      <version>1.568-SNAPSHOT</version>
       <scope>test</scope>
     </dependency>
     <!--
diff --git a/pom.xml b/pom.xml
index bafb3ba15def59630249485bd65e1084704f3dd1..bd84c7a125084d160758a83879f2ea3bb42a6db1 100644
--- a/pom.xml
+++ b/pom.xml
@@ -33,7 +33,7 @@ THE SOFTWARE.
 
   <groupId>org.jenkins-ci.main</groupId>
   <artifactId>pom</artifactId>
-  <version>1.567-SNAPSHOT</version>
+  <version>1.568-SNAPSHOT</version>
   <packaging>pom</packaging>
 
   <name>Jenkins main module</name>
diff --git a/test/pom.xml b/test/pom.xml
index c15ba55004175956d1c38819c77f23cc7466ebef..669fd5eb56a7b9695d88d47adf799cd4f872d5d6 100644
--- a/test/pom.xml
+++ b/test/pom.xml
@@ -29,7 +29,7 @@ THE SOFTWARE.
   <parent>
     <artifactId>pom</artifactId>
     <groupId>org.jenkins-ci.main</groupId>
-    <version>1.567-SNAPSHOT</version>
+    <version>1.568-SNAPSHOT</version>
   </parent>
   <groupId>org.jenkins-ci.main</groupId>
   <artifactId>jenkins-test-harness</artifactId>
@@ -103,9 +103,9 @@ THE SOFTWARE.
       <version>6.1.26</version>
     </dependency>
     <dependency>
-      <groupId>org.jvnet.hudson</groupId>
+      <groupId>org.jenkins-ci</groupId>
       <artifactId>test-annotations</artifactId>
-      <version>1.0</version>
+      <version>1.1</version>
       <scope>compile</scope>
       <!-- in this module we need this as a compile scope, whereas in the parent it's test -->
     </dependency>
diff --git a/test/src/test/java/hudson/ProcStarterTest.java b/test/src/test/java/hudson/ProcStarterTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..49ab5b6b5c3f4bd9adbdba23c1a9b08a97a4cc8c
--- /dev/null
+++ b/test/src/test/java/hudson/ProcStarterTest.java
@@ -0,0 +1,129 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2013 Oleg Nenashev <nenashev@synopsys.com>, Synopsys Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package hudson;
+
+import hudson.model.AbstractBuild;
+import hudson.model.AbstractProject;
+import hudson.model.BuildListener;
+import hudson.model.FreeStyleProject;
+import hudson.model.Run;
+import hudson.tasks.BuildWrapper;
+import hudson.tasks.BuildWrapperDescriptor;
+import java.io.IOException;
+import org.jvnet.hudson.test.Bug;
+import hudson.Launcher.DecoratedLauncher;
+import org.junit.Rule;
+import org.junit.Test;
+import org.jvnet.hudson.test.JenkinsRule;
+
+/**
+ * Contains tests for {@link ProcStarter} class.
+ * @author Oleg Nenashev <nenashev@synopsys.com>, Synopsys Inc.
+ * @since TODO: define a version
+ */
+public class ProcStarterTest {
+
+    @Rule
+    public JenkinsRule rule = new JenkinsRule();
+    
+    @Test
+    @Bug(20559)
+    public void testNonInitializedEnvsNPE() throws Exception {
+        // Create nodes and other test stuff
+        rule.hudson.setNumExecutors(0);
+        rule.createSlave();
+
+        // Create a job with test build wrappers
+        FreeStyleProject project = rule.createFreeStyleProject();
+        project.getBuildWrappersList().add(new DecoratedWrapper());
+        project.getBuildWrappersList().add(new EchoWrapper());
+
+        // Run the build. If NPE occurs, the test will fail
+        rule.buildAndAssertSuccess(project);
+    }
+
+    /**
+     * A stub descriptor for {@link BuildWrapper}s.
+     */
+    public abstract static class TestWrapperDescriptor extends BuildWrapperDescriptor {
+
+        @Override
+        public boolean isApplicable(AbstractProject<?, ?> ap) {
+            return true;
+        }
+
+        @Override
+        public String getDisplayName() {
+            return "testStub";
+        }
+    }
+
+    /**
+     * A wrapper, which contains a nested launch.
+     */
+    public static class EchoWrapper extends BuildWrapper {
+
+        @Override
+        public Environment setUp(AbstractBuild build, Launcher launcher, BuildListener listener) throws IOException, InterruptedException {
+            Launcher.ProcStarter starter = launcher.launch().cmds("echo", "Hello");
+            starter.start();
+            starter.join();
+            return new Environment() {
+            };
+        }
+        
+        @Extension
+        public static class DescriptorImpl extends TestWrapperDescriptor {
+        }
+    };
+
+    /**
+     * A wrapper, which decorates launchers.
+     */
+    public static class DecoratedWrapper extends BuildWrapper {
+
+        @Override
+        public Launcher decorateLauncher(AbstractBuild build, Launcher launcher, BuildListener listener) throws IOException, InterruptedException, Run.RunnerAbortedException {
+            final BuildListener l = listener;
+            return new DecoratedLauncher(launcher) {
+                @Override
+                public Proc launch(Launcher.ProcStarter starter) throws IOException {
+                    String[] envs = starter.envs(); // Finally, call envs()
+                    l.getLogger().println("[DecoratedWrapper]: Number of environment variables is "+envs.length); // Fail on null
+                    return super.launch(starter);
+                }
+            };
+        }
+
+        @Override
+        public Environment setUp(AbstractBuild build, Launcher launcher, BuildListener listener) throws IOException, InterruptedException {
+            return new Environment() {
+            };
+        }
+        
+        @Extension
+        public static class DescriptorImpl extends TestWrapperDescriptor {
+        }
+    };
+}
diff --git a/war/pom.xml b/war/pom.xml
index 9a3663d8320256337fbbe6b30b9cdaae0a406056..5704066c8a3b8528791c4e1b435d9704e25db5c3 100644
--- a/war/pom.xml
+++ b/war/pom.xml
@@ -28,7 +28,7 @@ THE SOFTWARE.
   <parent>
     <groupId>org.jenkins-ci.main</groupId>
     <artifactId>pom</artifactId>
-    <version>1.567-SNAPSHOT</version>
+    <version>1.568-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>