Bulk cleanup of hudson.slaves and jenkins.slaves (#3207)

* Bulk cleanup of hudson.slaves and jenkins.slaves

- [x] Use Jenkins.get() instead of the deprecated getInstance()
- [x] Remove unused imports
- [x] Use diamond type definitions where possible
- [x] Squash similar extension handlers
- [x] Other minor refactorings and NPE checks

* Update core/src/main/java/hudson/slaves/SlaveComputer.java

core/src/main/java/hudson/slaves/AbstractCloudSlave.java

@@ -67,7 +67,7 @@ public abstract class AbstractCloudSlave extends Slave {
             _terminate(new StreamTaskListener(System.out, Charset.defaultCharset()));
         } finally {
             try {
-                Jenkins.getInstance().removeNode(this);
+                Jenkins.get().removeNode(this);
             } catch (IOException e) {
                 LOGGER.log(Level.WARNING, "Failed to remove "+name,e);
             }

core/src/main/java/hudson/slaves/Cloud.java

@@ -34,7 +34,6 @@ import hudson.slaves.NodeProvisioner.PlannedNode;
 import hudson.model.Describable;
 import jenkins.model.Jenkins;
 import hudson.model.Node;
-import hudson.model.AbstractModelObject;
 import hudson.model.Label;
 import hudson.model.Descriptor;
 import hudson.security.ACL;
@@ -125,7 +124,7 @@ public abstract class Cloud extends Actionable implements ExtensionPoint, Descri
     }
 
     public ACL getACL() {
-        return Jenkins.getInstance().getAuthorizationStrategy().getACL(this);
+        return Jenkins.get().getAuthorizationStrategy().getACL(this);
     }
 
     /**
@@ -169,7 +168,7 @@ public abstract class Cloud extends Actionable implements ExtensionPoint, Descri
     public abstract boolean canProvision(Label label);
 
     public Descriptor<Cloud> getDescriptor() {
-        return Jenkins.getInstance().getDescriptorOrDie(getClass());
+        return Jenkins.get().getDescriptorOrDie(getClass());
     }
 
     /**
@@ -179,13 +178,13 @@ public abstract class Cloud extends Actionable implements ExtensionPoint, Descri
      *      Use {@link #all()} for read access, and {@link Extension} for registration.
      */
     @Deprecated
-    public static final DescriptorList<Cloud> ALL = new DescriptorList<Cloud>(Cloud.class);
+    public static final DescriptorList<Cloud> ALL = new DescriptorList<>(Cloud.class);
 
     /**
      * Returns all the registered {@link Cloud} descriptors.
      */
     public static DescriptorExtensionList<Cloud,Descriptor<Cloud>> all() {
-        return Jenkins.getInstance().<Cloud,Descriptor<Cloud>>getDescriptorList(Cloud.class);
+        return Jenkins.get().getDescriptorList(Cloud.class);
     }
 
     private static final PermissionScope PERMISSION_SCOPE = new PermissionScope(Cloud.class);

core/src/main/java/hudson/slaves/CloudRetentionStrategy.java

@@ -57,9 +57,7 @@ public class CloudRetentionStrategy extends RetentionStrategy<AbstractCloudCompu
                 LOGGER.log(Level.INFO, "Disconnecting {0}", c.getName());
                 try {
                     computerNode.terminate();
-                } catch (InterruptedException e) {
-                    LOGGER.log(WARNING, "Failed to terminate " + c.getName(), e);
-                } catch (IOException e) {
+                } catch (InterruptedException | IOException e) {
                     LOGGER.log(WARNING, "Failed to terminate " + c.getName(), e);
                 }
             }

core/src/main/java/hudson/slaves/CloudSlaveRetentionStrategy.java

@@ -47,7 +47,7 @@ public class CloudSlaveRetentionStrategy<T extends Computer> extends RetentionSt
      * To actually deallocate the resource tied to this {@link Node}, implement {@link Computer#onRemoved()}.
      */
     protected void kill(Node n) throws IOException {
-        Jenkins.getInstance().removeNode(n);
+        Jenkins.get().removeNode(n);
     }
 
     /**

core/src/main/java/hudson/slaves/ComputerConnectorDescriptor.java

@@ -12,7 +12,6 @@ import jenkins.model.Jenkins;
  */
 public abstract class ComputerConnectorDescriptor extends Descriptor<ComputerConnector> {
     public static DescriptorExtensionList<ComputerConnector,ComputerConnectorDescriptor> all() {
-        return Jenkins.getInstance().<ComputerConnector,ComputerConnectorDescriptor>
-                                    getDescriptorList(ComputerConnector.class);
+        return Jenkins.get().getDescriptorList(ComputerConnector.class);
     }
 }

core/src/main/java/hudson/slaves/ComputerLauncher.java

@@ -163,7 +163,7 @@ public abstract class ComputerLauncher extends AbstractDescribableImpl<ComputerL
      *      {@link jenkins.model.Jenkins#getDescriptorList(Class)} for read access.
      */
     @Deprecated
-    public static final DescriptorList<ComputerLauncher> LIST = new DescriptorList<ComputerLauncher>(ComputerLauncher.class);
+    public static final DescriptorList<ComputerLauncher> LIST = new DescriptorList<>(ComputerLauncher.class);
 
     /**
      * Given the output of "java -version" in <code>r</code>, determine if this

core/src/main/java/hudson/slaves/ComputerRetentionWork.java

@@ -46,7 +46,7 @@ public class ComputerRetentionWork extends PeriodicWork {
     /**
      * Use weak hash map to avoid leaking {@link Computer}.
      */
-    private final Map<Computer, Long> nextCheck = new WeakHashMap<Computer, Long>();
+    private final Map<Computer, Long> nextCheck = new WeakHashMap<>();
 
     public long getRecurrencePeriod() {
         return MIN;
@@ -59,7 +59,7 @@ public class ComputerRetentionWork extends PeriodicWork {
     @Override
     protected void doRun() {
         final long startRun = System.currentTimeMillis();
-        for (final Computer c : Jenkins.getInstance().getComputers()) {
+        for (final Computer c : Jenkins.get().getComputers()) {
             Queue.withLock(new Runnable() {
                 @Override
                 public void run() {

core/src/main/java/hudson/slaves/ConnectionActivityMonitor.java

@@ -58,7 +58,7 @@ public class ConnectionActivityMonitor extends AsyncPeriodicWork {
         if (!enabled)   return;
 
         long now = System.currentTimeMillis();
-        for (Computer c: Jenkins.getInstance().getComputers()) {
+        for (Computer c: Jenkins.get().getComputers()) {
             VirtualChannel ch = c.getChannel();
             if (ch instanceof Channel) {
                 Channel channel = (Channel) ch;

core/src/main/java/hudson/slaves/DelegatingComputerLauncher.java

@@ -100,7 +100,7 @@ public abstract class DelegatingComputerLauncher extends ComputerLauncher {
         public List<Descriptor<ComputerLauncher>> getApplicableDescriptors() {
             List<Descriptor<ComputerLauncher>> r = new ArrayList<Descriptor<ComputerLauncher>>();
             for (Descriptor<ComputerLauncher> d :
-                    Jenkins.getInstance().<ComputerLauncher, Descriptor<ComputerLauncher>>getDescriptorList(ComputerLauncher.class)) {
+                    Jenkins.get().getDescriptorList(ComputerLauncher.class)) {
                 if (DelegatingComputerLauncher.class.isAssignableFrom(d.getKlass().toJavaClass()))  continue;
                 r.add(d);
             }

core/src/main/java/hudson/slaves/JNLPLauncher.java

@@ -195,7 +195,7 @@ public class JNLPLauncher extends ComputerLauncher {
             // Causes JENKINS-45895 in the case of includes otherwise
             return DescriptorImpl.class.equals(getClass());
         }
-    };
+    }
 
     /**
      * Hides the JNLP launcher when the JNLP agent port is not enabled.
@@ -210,7 +210,7 @@ public class JNLPLauncher extends ComputerLauncher {
          */
         @Override
         public boolean filter(@CheckForNull Object context, @Nonnull Descriptor descriptor) {
-            return descriptor.clazz != JNLPLauncher.class || Jenkins.getInstance().getTcpSlaveAgentListener() != null;
+            return descriptor.clazz != JNLPLauncher.class || Jenkins.get().getTcpSlaveAgentListener() != null;
         }
 
         /**
@@ -218,7 +218,7 @@ public class JNLPLauncher extends ComputerLauncher {
          */
         @Override
         public boolean filterType(@Nonnull Class<?> contextClass, @Nonnull Descriptor descriptor) {
-            return descriptor.clazz != JNLPLauncher.class || Jenkins.getInstance().getTcpSlaveAgentListener() != null;
+            return descriptor.clazz != JNLPLauncher.class || Jenkins.get().getTcpSlaveAgentListener() != null;
         }
     }
 

core/src/main/java/hudson/slaves/NodeDescriptor.java

@@ -112,7 +112,7 @@ public abstract class NodeDescriptor extends Descriptor<Node> {
      * Returns all the registered {@link NodeDescriptor} descriptors.
      */
     public static DescriptorExtensionList<Node,NodeDescriptor> all() {
-        return Jenkins.getInstance().<Node,NodeDescriptor>getDescriptorList(Node.class);
+        return Jenkins.get().getDescriptorList(Node.class);
     }
 
     /**
@@ -121,10 +121,10 @@ public abstract class NodeDescriptor extends Descriptor<Node> {
      *      Use {@link #all()} for read access, and {@link Extension} for registration.
      */
     @Deprecated
-    public static final DescriptorList<Node> ALL = new DescriptorList<Node>(Node.class);
+    public static final DescriptorList<Node> ALL = new DescriptorList<>(Node.class);
 
     public static List<NodeDescriptor> allInstantiable() {
-        List<NodeDescriptor> r = new ArrayList<NodeDescriptor>();
+        List<NodeDescriptor> r = new ArrayList<>();
         for (NodeDescriptor d : all())
             if(d.isInstantiable())
                 r.add(d);

core/src/main/java/hudson/slaves/NodeList.java

@@ -49,7 +49,7 @@ import javax.annotation.CheckForNull;
  */
 public final class NodeList extends ArrayList<Node> {
     
-    private Map<String,Node> map = new HashMap<String, Node>(); 
+    private Map<String,Node> map = new HashMap<>();
     
     public NodeList() {
     }

core/src/main/java/hudson/slaves/NodeProperty.java

@@ -83,7 +83,7 @@ public abstract class NodeProperty<N extends Node> implements ReconfigurableDesc
     protected void setNode(N node) { this.node = node; }
 
     public NodePropertyDescriptor getDescriptor() {
-        return (NodePropertyDescriptor) Jenkins.getInstance().getDescriptorOrDie(getClass());
+        return (NodePropertyDescriptor) Jenkins.get().getDescriptorOrDie(getClass());
     }
 
     /**
@@ -178,7 +178,7 @@ public abstract class NodeProperty<N extends Node> implements ReconfigurableDesc
      * Lists up all the registered {@link NodeDescriptor}s in the system.
      */
     public static DescriptorExtensionList<NodeProperty<?>,NodePropertyDescriptor> all() {
-        return (DescriptorExtensionList) Jenkins.getInstance().getDescriptorList(NodeProperty.class);
+        return (DescriptorExtensionList) Jenkins.get().getDescriptorList(NodeProperty.class);
     }
 
     /**

core/src/main/java/hudson/slaves/NodePropertyDescriptor.java

@@ -55,6 +55,6 @@ public abstract class NodePropertyDescriptor extends PropertyDescriptor<NodeProp
         // preserve legacy behaviour, even if brain-dead stupid, where applying to Jenkins was the discriminator
         // note that it would be a mistake to assume Jenkins.getInstance().getClass() == Jenkins.class
         // the groovy code tested against app.class, so we replicate that exact logic.
-        return isApplicable(Jenkins.getInstance().getClass());
+        return isApplicable(Jenkins.get().getClass());
     }
 }

core/src/main/java/hudson/slaves/NodeProvisioner.java

@@ -38,6 +38,7 @@ import javax.annotation.Nonnull;
 import javax.annotation.concurrent.GuardedBy;
 import java.awt.Color;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.concurrent.Future;
 import java.util.concurrent.ExecutionException;
 import java.util.List;
@@ -127,7 +128,7 @@ public class NodeProvisioner {
     private final Label label;
 
     private final AtomicReference<List<PlannedNode>> pendingLaunches
-            = new AtomicReference<List<PlannedNode>>(new ArrayList<PlannedNode>());
+            = new AtomicReference<>(new ArrayList<>());
 
     private final Lock provisioningLock = new ReentrantLock();
 
@@ -159,7 +160,7 @@ public class NodeProvisioner {
      * @since 1.401
      */
     public List<PlannedNode> getPendingLaunches() {
-        return new ArrayList<PlannedNode>(pendingLaunches.get());
+        return new ArrayList<>(pendingLaunches.get());
     }
 
     /**
@@ -207,15 +208,14 @@ public class NodeProvisioner {
             Queue.withLock(new Runnable() {
                 @Override
                 public void run() {
-                    Jenkins jenkins = Jenkins.getInstance();
+                    Jenkins jenkins = Jenkins.get();
                     // clean up the cancelled launch activity, then count the # of executors that we are about to
                     // bring up.
 
                     int plannedCapacitySnapshot = 0;
 
-                    List<PlannedNode> snapPendingLaunches = new ArrayList<PlannedNode>(pendingLaunches.get());
-                    for (Iterator<PlannedNode> itr = snapPendingLaunches.iterator(); itr.hasNext(); ) {
-                        PlannedNode f = itr.next();
+                    List<PlannedNode> snapPendingLaunches = new ArrayList<>(pendingLaunches.get());
+                    for (PlannedNode f : snapPendingLaunches) {
                         if (f.future.isDone()) {
                             try {
                                 Node node = null;
@@ -263,7 +263,7 @@ public class NodeProvisioner {
                             } finally {
                                 while (true) {
                                     List<PlannedNode> orig = pendingLaunches.get();
-                                    List<PlannedNode> repl = new ArrayList<PlannedNode>(orig);
+                                    List<PlannedNode> repl = new ArrayList<>(orig);
                                     // the contract for List.remove(o) is that the first element i where
                                     // (o==null ? get(i)==null : o.equals(get(i)))
                                     // is true will be removed from the list
@@ -305,15 +305,15 @@ public class NodeProvisioner {
                                 new Object[]{queueLengthSnapshot, availableSnapshot});
                         provisioningState = null;
                     } else {
-                        provisioningState = new StrategyState(snapshot, label, plannedCapacitySnapshot);;
+                        provisioningState = new StrategyState(snapshot, label, plannedCapacitySnapshot);
                     }
                 }
             });
 
             if (provisioningState != null) {
-                List<Strategy> strategies = Jenkins.getInstance().getExtensionList(Strategy.class);
+                List<Strategy> strategies = Jenkins.get().getExtensionList(Strategy.class);
                 for (Strategy strategy : strategies.isEmpty()
-                        ? Arrays.<Strategy>asList(new StandardStrategyImpl())
+                        ? Collections.<Strategy>singletonList(new StandardStrategyImpl())
                         : strategies) {
                     LOGGER.log(Level.FINER, "Consulting {0} provisioning strategy with state {1}",
                             new Object[]{strategy, provisioningState});
@@ -580,7 +580,7 @@ public class NodeProvisioner {
             }
             while (!plannedNodes.isEmpty()) {
                 List<PlannedNode> orig = pendingLaunches.get();
-                List<PlannedNode> repl = new ArrayList<PlannedNode>(orig);
+                List<PlannedNode> repl = new ArrayList<>(orig);
                 repl.addAll(plannedNodes);
                 if (pendingLaunches.compareAndSet(orig, repl)) {
                     if (additionalPlannedCapacity > 0) {
@@ -687,7 +687,7 @@ public class NodeProvisioner {
                             });
 
                     CLOUD:
-                    for (Cloud c : Jenkins.getInstance().clouds) {
+                    for (Cloud c : Jenkins.get().clouds) {
                         if (excessWorkload < 0) {
                             break;  // enough agents allocated
                         }
@@ -803,9 +803,9 @@ public class NodeProvisioner {
 
         @Override
         protected void doRun() {
-            Jenkins h = Jenkins.getInstance();
-            h.unlabeledNodeProvisioner.update();
-            for( Label l : h.getLabels() )
+            Jenkins j = Jenkins.get();
+            j.unlabeledNodeProvisioner.update();
+            for( Label l : j.getLabels() )
                 l.nodeProvisioner.update();
         }
     }

core/src/main/java/hudson/slaves/RetentionStrategy.java

@@ -104,7 +104,7 @@ public abstract class RetentionStrategy<T extends Computer> extends AbstractDesc
      * Returns all the registered {@link RetentionStrategy} descriptors.
      */
     public static DescriptorExtensionList<RetentionStrategy<?>,Descriptor<RetentionStrategy<?>>> all() {
-        return (DescriptorExtensionList) Jenkins.getInstance().getDescriptorList(RetentionStrategy.class);
+        return (DescriptorExtensionList) Jenkins.get().getDescriptorList(RetentionStrategy.class);
     }
 
     /**
@@ -216,8 +216,8 @@ public abstract class RetentionStrategy<T extends Computer> extends AbstractDesc
         @GuardedBy("hudson.model.Queue.lock")
         public long check(final SlaveComputer c) {
             if (c.isOffline() && c.isLaunchSupported()) {
-                final HashMap<Computer, Integer> availableComputers = new HashMap<Computer, Integer>();
-                for (Computer o : Jenkins.getInstance().getComputers()) {
+                final HashMap<Computer, Integer> availableComputers = new HashMap<>();
+                for (Computer o : Jenkins.get().getComputers()) {
                     if ((o.isOnline() || o.isConnecting()) && o.isPartiallyIdle() && o.isAcceptingTasks()) {
                         final int idleExecutors = o.countIdle();
                         if (idleExecutors>0)

core/src/main/java/hudson/slaves/SlaveComputer.java

@@ -26,6 +26,7 @@ package hudson.slaves;
 import hudson.AbortException;
 import hudson.FilePath;
 import hudson.Functions;
+import hudson.RestrictedSince;
 import hudson.Util;
 import hudson.console.ConsoleLogFilter;
 import hudson.model.Computer;
@@ -557,7 +558,11 @@ public class SlaveComputer extends Computer {
 
     static class LoadingPrefetchCacheCount extends MasterToSlaveCallable<Integer,RuntimeException> {
         @Override public Integer call() {
-            return Channel.current().classLoadingPrefetchCacheCount.get();
+            Channel c = Channel.current();
+            if (c == null) {
+                return -1;
+            }
+            return c.classLoadingPrefetchCacheCount.get();
         }
     }
 
@@ -569,7 +574,7 @@ public class SlaveComputer extends Computer {
         @Override public Long call() {
             Channel c = Channel.current();
             if (c == null) {
-                return Long.valueOf(-1);
+                return -1L;
             }
             return resource ? c.resourceLoadingTime.get() : c.classLoadingTime.get();
         }
@@ -695,7 +700,7 @@ public class SlaveComputer extends Computer {
             SecurityContextHolder.setContext(old);
         }
         log.println("Agent successfully connected and online");
-        Jenkins.getInstance().getQueue().scheduleMaintenance();
+        Jenkins.get().getQueue().scheduleMaintenance();
     }
 
     @Override
@@ -993,13 +998,15 @@ public class SlaveComputer extends Computer {
     /**
      * Helper method for Jelly.
      */
+    @Restricted(DoNotUse.class)
+    @RestrictedSince("TODO")
     public static List<SlaveSystemInfo> getSystemInfoExtensions() {
         return SlaveSystemInfo.all();
     }
 
     private static class SlaveLogFetcher extends MasterToSlaveCallable<List<LogRecord>,RuntimeException> {
         public List<LogRecord> call() {
-            return new ArrayList<LogRecord>(SLAVE_LOG_HANDLER.getView());
+            return new ArrayList<>(SLAVE_LOG_HANDLER.getView());
         }
     }
 

core/src/main/java/hudson/slaves/WorkspaceList.java

@@ -112,7 +112,9 @@ public final class WorkspaceList {
         public final @Nonnull FilePath path;
 
         protected Lease(@Nonnull FilePath path) {
-            path.getRemote(); // null check
+            if (path == null) { // Protection from old API
+                throw new NullPointerException("The specified FilePath is null");
+            }
             this.path = path;
         }
 
@@ -153,7 +155,7 @@ public final class WorkspaceList {
         }
     }
 
-    private final Map<FilePath,Entry> inUse = new HashMap<FilePath,Entry>();
+    private final Map<FilePath,Entry> inUse = new HashMap<>();
 
     public WorkspaceList() {
     }

core/src/main/java/jenkins/slaves/DefaultJnlpSlaveReceiver.java

@@ -56,7 +56,7 @@ public class DefaultJnlpSlaveReceiver extends JnlpAgentReceiver {
 
     @Override
     public boolean owns(String clientName) {
-        Computer computer = Jenkins.getInstance().getComputer(clientName);
+        Computer computer = Jenkins.get().getComputer(clientName);
         return computer != null;
     }
 
@@ -83,7 +83,7 @@ public class DefaultJnlpSlaveReceiver extends JnlpAgentReceiver {
     @Override
     public void afterProperties(@NonNull JnlpConnectionState event) {
         String clientName = event.getProperty(JnlpConnectionState.CLIENT_NAME_KEY);
-        SlaveComputer computer = (SlaveComputer) Jenkins.getInstance().getComputer(clientName);
+        SlaveComputer computer = (SlaveComputer) Jenkins.get().getComputer(clientName);
         if (computer == null) {
             event.reject(new ConnectionRefusalException(String.format("%s is not a JNLP agent", clientName)));
             return;

core/src/main/java/jenkins/slaves/DeprecatedAgentProtocolMonitor.java

@@ -60,7 +60,7 @@ public class DeprecatedAgentProtocolMonitor extends AdministrativeMonitor {
 
     @Override
     public boolean isActivated() {
-        final Set<String> agentProtocols = Jenkins.getInstance().getAgentProtocols();
+        final Set<String> agentProtocols = Jenkins.get().getAgentProtocols();
         for (String name : agentProtocols) {
             AgentProtocol pr = AgentProtocol.of(name);
             if (pr != null && pr.isDeprecated()) {
@@ -79,7 +79,7 @@ public class DeprecatedAgentProtocolMonitor extends AdministrativeMonitor {
     @CheckForNull
     public static String getDeprecatedProtocolsString() {
         final List<String> deprecatedProtocols = new ArrayList<>();
-        final Set<String> agentProtocols = Jenkins.getInstance().getAgentProtocols();
+        final Set<String> agentProtocols = Jenkins.get().getAgentProtocols();
         for (String name : agentProtocols) {
             AgentProtocol pr = AgentProtocol.of(name);
             if (pr != null && pr.isDeprecated()) {

core/src/main/java/jenkins/slaves/JnlpSlaveAgentProtocol.java

@@ -7,15 +7,12 @@ import hudson.model.Computer;
 import java.io.IOException;
 import java.net.Socket;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.logging.Logger;
-import javax.annotation.Nonnull;
 import javax.inject.Inject;
 import jenkins.AgentProtocol;
 import jenkins.model.Jenkins;
 import jenkins.security.HMACConfidentialKey;
 import org.jenkinsci.Symbol;
-import org.jenkinsci.remoting.engine.JnlpClientDatabase;
 import org.jenkinsci.remoting.engine.JnlpConnectionState;
 import org.jenkinsci.remoting.engine.JnlpProtocol1Handler;
 
@@ -104,4 +101,5 @@ public class JnlpSlaveAgentProtocol extends AgentProtocol {
                 ExtensionList.lookup(JnlpAgentReceiver.class));
     }
 
+
 }

core/src/main/java/jenkins/slaves/JnlpSlaveAgentProtocol2.java

@@ -6,12 +6,9 @@ import hudson.model.Computer;
 import java.io.IOException;
 import java.net.Socket;
 import java.util.Collections;
-import java.util.HashMap;
-import javax.annotation.Nonnull;
 import javax.inject.Inject;
 import jenkins.AgentProtocol;
 import org.jenkinsci.Symbol;
-import org.jenkinsci.remoting.engine.JnlpClientDatabase;
 import org.jenkinsci.remoting.engine.JnlpConnectionState;
 import org.jenkinsci.remoting.engine.JnlpProtocol2Handler;
 

core/src/main/java/jenkins/slaves/JnlpSlaveAgentProtocol3.java

@@ -8,14 +8,11 @@ import hudson.model.Computer;
 import java.io.IOException;
 import java.net.Socket;
 import java.util.Collections;
-import java.util.HashMap;
-import javax.annotation.Nonnull;
 import javax.inject.Inject;
 import jenkins.AgentProtocol;
 import jenkins.model.Jenkins;
 import jenkins.util.SystemProperties;
 import org.jenkinsci.Symbol;
-import org.jenkinsci.remoting.engine.JnlpClientDatabase;
 import org.jenkinsci.remoting.engine.JnlpConnectionState;
 import org.jenkinsci.remoting.engine.JnlpProtocol3Handler;
 import org.kohsuke.accmod.Restricted;

core/src/main/java/jenkins/slaves/JnlpSlaveAgentProtocol4.java

@@ -37,8 +37,6 @@ import java.security.cert.CertificateException;
 import java.security.cert.X509Certificate;
 import java.security.interfaces.RSAPrivateKey;
 import java.util.Collections;
-import java.util.HashMap;
-import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;

core/src/main/java/jenkins/slaves/PingFailureAnalyzer.java

@@ -28,6 +28,6 @@ public abstract class PingFailureAnalyzer implements ExtensionPoint {
     public abstract void onPingFailure(Channel c, Throwable cause) throws IOException;
 
     public static ExtensionList<PingFailureAnalyzer> all() {
-        return Jenkins.getInstance().getExtensionList(PingFailureAnalyzer.class);
+        return Jenkins.get().getExtensionList(PingFailureAnalyzer.class);
     }
 }

core/src/main/java/jenkins/slaves/RemotingWorkDirSettings.java

@@ -124,7 +124,7 @@ public class RemotingWorkDirSettings implements Describable<RemotingWorkDirSetti
 
     @Override
     public Descriptor<RemotingWorkDirSettings> getDescriptor() {
-        return Jenkins.getInstance().getDescriptor(RemotingWorkDirSettings.class);
+        return Jenkins.get().getDescriptor(RemotingWorkDirSettings.class);
     }
 
     /**
@@ -152,7 +152,7 @@ public class RemotingWorkDirSettings implements Describable<RemotingWorkDirSetti
         
         if (!DEFAULT_INTERNAL_DIR.equals(internalDir)) {
             args.add("-internalDir");
-            args.add(internalDir);;
+            args.add(internalDir);
         }
         
         if (failIfWorkDirIsMissing) {

core/src/main/java/jenkins/slaves/restarter/JnlpSlaveRestarterInstaller.java

@@ -53,7 +53,7 @@ public class JnlpSlaveRestarterInstaller extends ComputerListener implements Ser
 
     private static void install(Computer c, TaskListener listener) {
         try {
-            final List<SlaveRestarter> restarters = new ArrayList<SlaveRestarter>(SlaveRestarter.all());
+            final List<SlaveRestarter> restarters = new ArrayList<>(SlaveRestarter.all());
 
             VirtualChannel ch = c.getChannel();
             if (ch==null) return;  // defensive check

core/src/main/java/jenkins/slaves/restarter/UnixSlaveRestarter.java

@@ -37,13 +37,7 @@ public class UnixSlaveRestarter extends SlaveRestarter {
             LIBC.execv("positively/no/such/executable", new StringArray(new String[]{"a","b","c"}));
 
             return true;
-        } catch (UnsupportedOperationException e) {
-            LOGGER.log(FINE, getClass()+" unsuitable", e);
-            return false;
-        } catch (LinkageError e) {
-            LOGGER.log(FINE, getClass()+" unsuitable", e);
-            return false;
-        } catch (IOException e) {
+        } catch (UnsupportedOperationException | LinkageError | IOException e) {
             LOGGER.log(FINE, getClass()+" unsuitable", e);
             return false;
         }

core/src/main/java/jenkins/slaves/restarter/WinswSlaveRestarter.java

@@ -24,10 +24,7 @@ public class WinswSlaveRestarter extends SlaveRestarter {
                 return false;   // not under winsw
 
             return exec("status") ==0;
-        } catch (InterruptedException e) {
-            LOGGER.log(FINE, getClass()+" unsuitable", e);
-            return false;
-        } catch (IOException e) {
+        } catch (InterruptedException | IOException e) {
             LOGGER.log(FINE, getClass()+" unsuitable", e);
             return false;
         }