Merge pull request #1468 from synopsys-arc-oss/JENKINS-25734

[JENKINS-25734] - Prevent NPE in Executor/causeOfDeath page on "expected thread death"

core/src/main/java/hudson/Functions.java

@@ -152,6 +152,7 @@ import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import hudson.util.RunList;
 import java.util.concurrent.atomic.AtomicLong;
+import javax.annotation.CheckForNull;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
 
@@ -1392,7 +1393,17 @@ public class Functions {
         return value!=null ? value : defaultValue;
     }
 
-    public static String printThrowable(Throwable t) {
+    /**
+     * Gets info about the specified {@link Throwable}.
+     * @param t Input {@link Throwable}
+     * @return If {@link Throwable} is not null, a summary info with the 
+     *      stacktrace will be returned. Otherwise, the method returns a default
+     *      "No exception details" string.
+     */
+    public static String printThrowable(@CheckForNull Throwable t) {
+        if (t == null) {
+            return Messages.Functions_NoExceptionDetails();
+        }
         StringWriter sw = new StringWriter();
         t.printStackTrace(new PrintWriter(sw));
         return sw.toString();

core/src/main/java/hudson/model/Executor.java

@@ -627,7 +627,7 @@ public class Executor extends Thread implements ModelObject {
      * @return null if the death is expected death or the thread {@link #isActive}.
      * @since 1.142
      */
-    public Throwable getCauseOfDeath() {
+    public @CheckForNull Throwable getCauseOfDeath() {
         return causeOfDeath;
     }
 

core/src/main/resources/hudson/Messages.properties

@@ -67,4 +67,6 @@ AboutJenkins.Description=See the version and license information.
 ProxyConfiguration.TestUrlRequired=Test URL is required.
 ProxyConfiguration.FailedToConnectViaProxy=Failed to connect to {0}.
 ProxyConfiguration.FailedToConnect=Failed to connect to {0} (code {1}).
-ProxyConfiguration.Success=Success
\ No newline at end of file
+ProxyConfiguration.Success=Success
+
+Functions.NoExceptionDetails=No Exception details
\ No newline at end of file