diff --git a/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/async/RedirectedAsyncOperation.java b/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/async/RedirectedAsyncOperation.java
index 0063ec0e990c..49f7ae24abda 100644
--- a/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/async/RedirectedAsyncOperation.java
+++ b/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/async/RedirectedAsyncOperation.java
@@ -7,15 +7,15 @@
 public abstract class RedirectedAsyncOperation<S, T> implements AsyncOperation<T> {
 
     protected final AsyncOperation<S> source;
-    private final AsyncOperationListenImpl<T> listenImpl;
+    private AsyncOperationListenImpl<T> listenImpl;
 
     public RedirectedAsyncOperation(AsyncOperation<S> source) {
         this.source = source;
+    }
+
+    void listen() {
         this.listenImpl = new AsyncOperationListenImpl<>(this);
-        source.register(new AsyncCallback<S>() {
-            @Override
-            public void done(AsyncOperation<S> op) { notifyDone(); }
-        });
+        source.register(op -> notifyDone());
     }
 
     private void notifyDone() {
diff --git a/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/http/JsonHttpResult.java b/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/http/JsonHttpResult.java
index f62c97696ba8..eae8fb8ba324 100644
--- a/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/http/JsonHttpResult.java
+++ b/clustercontroller-utils/src/main/java/com/yahoo/vespa/clustercontroller/utils/communication/http/JsonHttpResult.java
@@ -6,7 +6,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 
-public class JsonHttpResult extends HttpResult {
+public final class JsonHttpResult extends HttpResult {
 
     private static final ObjectMapper mapper = new ObjectMapper();
 
diff --git a/clustercontroller-utils/src/test/java/com/yahoo/vespa/clustercontroller/utils/communication/async/AsyncTest.java b/clustercontroller-utils/src/test/java/com/yahoo/vespa/clustercontroller/utils/communication/async/AsyncTest.java
index 1a5ce12be923..1f5351302011 100644
--- a/clustercontroller-utils/src/test/java/com/yahoo/vespa/clustercontroller/utils/communication/async/AsyncTest.java
+++ b/clustercontroller-utils/src/test/java/com/yahoo/vespa/clustercontroller/utils/communication/async/AsyncTest.java
@@ -103,12 +103,13 @@ public void done(AsyncOperation<String> op) {
     void testRedirectedOperation() {
         {
             final AsyncOperationImpl<String> op = new AsyncOperationImpl<>("test", "desc");
-            AsyncOperation<Integer> deleteRequest = new RedirectedAsyncOperation<String, Integer>(op) {
+            var deleteRequest = new RedirectedAsyncOperation<String, Integer>(op) {
                 @Override
                 public Integer getResult() {
                     return Integer.valueOf(op.getResult());
                 }
             };
+            deleteRequest.listen();
             final LinkedList<Integer> result = new LinkedList<>();
             deleteRequest.register(new AsyncCallback<Integer>() {
                 @Override
@@ -134,12 +135,13 @@ public void done(AsyncOperation<Integer> op) {
         }
         {
             final AsyncOperationImpl<String> op = new AsyncOperationImpl<>("test", "desc");
-            AsyncOperation<Integer> deleteRequest = new RedirectedAsyncOperation<String, Integer>(op) {
+            var deleteRequest = new RedirectedAsyncOperation<String, Integer>(op) {
                 @Override
                 public Integer getResult() {
                     return Integer.valueOf(op.getResult());
                 }
             };
+            deleteRequest.listen();
             op.setFailure(new Exception("foo"));
             assertTrue(deleteRequest.isDone());
             assertEquals("foo", deleteRequest.getCause().getMessage());
@@ -182,7 +184,7 @@ public void successfullyDone(AsyncOperation<String> source) {
         }
     }
 
-    private abstract class StressThread implements Runnable {
+    private abstract static class StressThread implements Runnable {
         private final Object monitor;
         private boolean running = true;
 
@@ -210,20 +212,20 @@ public void run() {
         public abstract void doTask();
     }
 
-    private abstract class AsyncOpStressThread extends StressThread {
+    private abstract static class AsyncOpStressThread extends StressThread {
         public AsyncOperationImpl<String> op;
         public AsyncOpStressThread(Object monitor) { super(monitor); }
         @Override
         public boolean hasTask() { return op != null; }
     }
 
-    private class Completer extends AsyncOpStressThread {
+    private static class Completer extends AsyncOpStressThread {
         public Completer(Object monitor) { super(monitor); }
         @Override
         public void doTask() { op.setResult("foo"); op = null; }
     }
 
-    private class Listener extends AsyncOpStressThread implements AsyncCallback<String> {
+    private static class Listener extends AsyncOpStressThread implements AsyncCallback<String> {
         int counter = 0;
         int unset = 0;
         int priorReg = 0;
diff --git a/container-disc/src/main/java/com/yahoo/container/jdisc/DataplaneProxyService.java b/container-disc/src/main/java/com/yahoo/container/jdisc/DataplaneProxyService.java
index e1a753ddf275..71b9ad542b78 100644
--- a/container-disc/src/main/java/com/yahoo/container/jdisc/DataplaneProxyService.java
+++ b/container-disc/src/main/java/com/yahoo/container/jdisc/DataplaneProxyService.java
@@ -23,7 +23,7 @@
  *
  * @author mortent
  */
-public class DataplaneProxyService extends AbstractComponent {
+public final class DataplaneProxyService extends AbstractComponent {
 
     private static final Logger logger = Logger.getLogger(DataplaneProxyService.class.getName());
     private static final String PREFIX = "/opt/vespa";