diff --git a/cli/src/main/java/hudson/cli/CLI.java b/cli/src/main/java/hudson/cli/CLI.java
index bffbb5705a..05e52a6d25 100644
--- a/cli/src/main/java/hudson/cli/CLI.java
+++ b/cli/src/main/java/hudson/cli/CLI.java
@@ -261,7 +261,7 @@ public class CLI {
         }
 
         if(args.isEmpty())
-            args = Arrays.asList("help"); // default to help
+            args = Collections.singletonList("help"); // default to help
 
         if (mode == null) {
             mode = Mode.HTTP;
diff --git a/cli/src/main/java/hudson/cli/FlightRecorderInputStream.java b/cli/src/main/java/hudson/cli/FlightRecorderInputStream.java
index ebdd18a192..0850bcb7bf 100644
--- a/cli/src/main/java/hudson/cli/FlightRecorderInputStream.java
+++ b/cli/src/main/java/hudson/cli/FlightRecorderInputStream.java
@@ -1,5 +1,7 @@
 package hudson.cli;
 
+import edu.umd.cs.findbugs.annotations.NonNull;
+
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -92,7 +94,7 @@ class FlightRecorderInputStream extends InputStream {
     }
 
     @Override
-    public int read(byte[] b, int off, int len) throws IOException {
+    public int read(@NonNull byte[] b, int off, int len) throws IOException {
         len = source.read(b, off, len);
         if (len>0)
             recorder.write(b,off,len);
@@ -157,7 +159,7 @@ class FlightRecorderInputStream extends InputStream {
         }
         
         /** @author @roadrunner2 */
-        @Override public synchronized void write(byte[] buf, int off, int len) {
+        @Override public synchronized void write(@NonNull byte[] buf, int off, int len) {
             // no point in trying to copy more than capacity; this also simplifies logic below
             if (len > capacity) {
                 off += (len - capacity);
diff --git a/cli/src/main/java/hudson/cli/PlainCLIProtocol.java b/cli/src/main/java/hudson/cli/PlainCLIProtocol.java
index 5359b7c738..7018d4770c 100644
--- a/cli/src/main/java/hudson/cli/PlainCLIProtocol.java
+++ b/cli/src/main/java/hudson/cli/PlainCLIProtocol.java
@@ -36,6 +36,8 @@ import java.nio.channels.ClosedChannelException;
 import java.nio.channels.ReadPendingException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.io.input.BoundedInputStream;
 import org.apache.commons.io.input.CountingInputStream;
@@ -233,11 +235,11 @@ class PlainCLIProtocol {
                     send(op, new byte[] {(byte) b});
                 }
                 @Override
-                public void write(byte[] b, int off, int len) throws IOException {
+                public void write(@NonNull byte[] b, int off, int len) throws IOException {
                     send(op, b, off, len);
                 }
                 @Override
-                public void write(byte[] b) throws IOException {
+                public void write(@NonNull byte[] b) throws IOException {
                     send(op, b);
                 }
             };
diff --git a/cli/src/main/java/hudson/cli/PrivateKeyProvider.java b/cli/src/main/java/hudson/cli/PrivateKeyProvider.java
index fbd4f332da..579aae6e53 100644
--- a/cli/src/main/java/hudson/cli/PrivateKeyProvider.java
+++ b/cli/src/main/java/hudson/cli/PrivateKeyProvider.java
@@ -52,7 +52,7 @@ import org.apache.sshd.common.util.security.SecurityUtils;
  */
 public class PrivateKeyProvider {
 
-    private List<KeyPair> privateKeys = new ArrayList<KeyPair>();
+    private List<KeyPair> privateKeys = new ArrayList<>();
 
     /**
      * Get keys read so far.
diff --git a/cli/src/main/java/hudson/util/QuotedStringTokenizer.java b/cli/src/main/java/hudson/util/QuotedStringTokenizer.java
index 55db964b09..6a82382d26 100644
--- a/cli/src/main/java/hudson/util/QuotedStringTokenizer.java
+++ b/cli/src/main/java/hudson/util/QuotedStringTokenizer.java
@@ -129,7 +129,7 @@ public class QuotedStringTokenizer
     }
 
     public String[] toArray() {
-        List<String> r = new ArrayList<String>();
+        List<String> r = new ArrayList<>();
         while(hasMoreTokens())
             r.add(nextToken());
         return r.toArray(new String[r.size()]);
diff --git a/core/src/main/java/hudson/Functions.java b/core/src/main/java/hudson/Functions.java
index bfac3b9728..49f4dd6c0a 100644
--- a/core/src/main/java/hudson/Functions.java
+++ b/core/src/main/java/hudson/Functions.java
@@ -2196,11 +2196,7 @@ public class Functions {
 
     public static ArrayList<CLICommand> getCLICommands() {
         ArrayList<CLICommand> all = new ArrayList<>(CLICommand.all());
-        Collections.sort(all, new Comparator<CLICommand>() {
-            public int compare(CLICommand cliCommand, CLICommand cliCommand1) {
-                return cliCommand.getName().compareTo(cliCommand1.getName());
-            }
-        });
+        all.sort(Comparator.comparing(CLICommand::getName));
         return all;
     }
 
diff --git a/core/src/main/java/hudson/PluginWrapper.java b/core/src/main/java/hudson/PluginWrapper.java
index 0442248c2d..2a94146694 100644
--- a/core/src/main/java/hudson/PluginWrapper.java
+++ b/core/src/main/java/hudson/PluginWrapper.java
@@ -221,7 +221,7 @@ public class PluginWrapper implements Comparable<PluginWrapper>, ModelObject {
      * The core can depend on a plugin if it is bundled. Sometimes it's the only thing that
      * depends on the plugin e.g. UI support library bundle plugin.
      */
-    private static Set<String> CORE_ONLY_DEPENDANT = ImmutableSet.copyOf(Arrays.asList("jenkins-core"));
+    private static Set<String> CORE_ONLY_DEPENDANT = ImmutableSet.copyOf(Collections.singletonList("jenkins-core"));
 
     /**
      * Set the list of components that depend on this plugin.
diff --git a/core/src/main/java/hudson/model/Actionable.java b/core/src/main/java/hudson/model/Actionable.java
index 17c5fa3b8e..e513897a8c 100644
--- a/core/src/main/java/hudson/model/Actionable.java
+++ b/core/src/main/java/hudson/model/Actionable.java
@@ -146,7 +146,7 @@ public abstract class Actionable extends AbstractModelObject implements ModelObj
      * Note: calls to {@link #getAllActions()} that happen before calls to this method may not see the update.
      * <strong>Note: this method will always modify the actions</strong>
      */
-    @SuppressWarnings({"ConstantConditions","deprecation"})
+    @SuppressWarnings({"ConstantConditions"})
     @SuppressFBWarnings("RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE")
     public void addAction(@NonNull Action a) {
         if(a==null) {
diff --git a/core/src/main/java/hudson/security/csrf/CrumbFilter.java b/core/src/main/java/hudson/security/csrf/CrumbFilter.java
index 8d28351240..c8a0f80b61 100644
--- a/core/src/main/java/hudson/security/csrf/CrumbFilter.java
+++ b/core/src/main/java/hudson/security/csrf/CrumbFilter.java
@@ -77,7 +77,7 @@ public class CrumbFilter implements Filter {
 
         // Copied from Stapler#canonicalPath
         private static String canonicalPath(String path) {
-            List<String> r = new ArrayList<String>(Arrays.asList(path.split("/+")));
+            List<String> r = new ArrayList<>(Arrays.asList(path.split("/+")));
             for (int i=0; i<r.size(); ) {
                 if (r.get(i).length()==0 || r.get(i).equals(".")) {
                     // empty token occurs for example, "".split("/+") is [""]
diff --git a/core/src/main/java/hudson/util/jna/Advapi32.java b/core/src/main/java/hudson/util/jna/Advapi32.java
index 288e9d5a33..3d8e2263b8 100644
--- a/core/src/main/java/hudson/util/jna/Advapi32.java
+++ b/core/src/main/java/hudson/util/jna/Advapi32.java
@@ -24,6 +24,7 @@ import com.sun.jna.ptr.PointerByReference;
 import com.sun.jna.ptr.IntByReference;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 /**
@@ -360,7 +361,7 @@ typedef struct _SERVICE_TABLE_ENTRY {
 
     @Override
     protected List getFieldOrder() {
-        return Arrays.asList();
+        return Collections.emptyList();
     }
   }
 
diff --git a/core/src/main/java/jenkins/util/xml/FilteredFunctionContext.java b/core/src/main/java/jenkins/util/xml/FilteredFunctionContext.java
index bc2d3ad5d1..06383e134a 100644
--- a/core/src/main/java/jenkins/util/xml/FilteredFunctionContext.java
+++ b/core/src/main/java/jenkins/util/xml/FilteredFunctionContext.java
@@ -53,7 +53,7 @@ public class FilteredFunctionContext implements FunctionContext {
      * Default set of "bad" function names.
      */
     private static final Set<String> DEFAULT_ILLEGAL_FUNCTIONS = Collections.unmodifiableSet(new HashSet<>(
-            Arrays.asList("document")
+            Collections.singletonList("document")
     ));
     private final FunctionContext base;
     private final Set<String> illegalFunctions;
diff --git a/core/src/main/java/jenkins/util/xstream/XStreamDOM.java b/core/src/main/java/jenkins/util/xstream/XStreamDOM.java
index b8aa7ef38c..2653325a23 100644
--- a/core/src/main/java/jenkins/util/xstream/XStreamDOM.java
+++ b/core/src/main/java/jenkins/util/xstream/XStreamDOM.java
@@ -307,9 +307,12 @@ public class XStreamDOM {
                     if (node.children.get(i).tagName.equals(child.tagName))
                         count++;
                 boolean more = false;
-                for (int i=pos; !more && i<node.children.size(); i++)
-                    if (node.children.get(i).tagName.equals(child.tagName))
+                for (int i = pos; i < node.children.size(); i++) {
+                    if (node.children.get(i).tagName.equals(child.tagName)) {
                         more = true;
+                        break;
+                    }
+                }
 
                 if (count==0 && !more)  return child.tagName;   // sole child
                 return child.tagName+'['+count+']';