diff --git a/akka-actor/src/main/scala/akka/actor/FaultHandling.scala b/akka-actor/src/main/scala/akka/actor/FaultHandling.scala
index ab93cfee88..fbee491664 100644
--- a/akka-actor/src/main/scala/akka/actor/FaultHandling.scala
+++ b/akka-actor/src/main/scala/akka/actor/FaultHandling.scala
@@ -234,8 +234,8 @@ object SupervisorStrategy extends SupervisorStrategyLowPriorityImplicits {
 
   private[akka] def maxNrOfRetriesOption(maxNrOfRetries: Int): Option[Int] =
     if (maxNrOfRetries < 0) None else Some(maxNrOfRetries)
-    
-  private[akka] val escalateDefault = (_: Any) => Escalate
+
+  private[akka] val escalateDefault = (_: Any) ⇒ Escalate
 }
 
 /**
diff --git a/akka-actor/src/main/scala/akka/pattern/CircuitBreaker.scala b/akka-actor/src/main/scala/akka/pattern/CircuitBreaker.scala
index bfcf3a3783..8a423c12b3 100644
--- a/akka-actor/src/main/scala/akka/pattern/CircuitBreaker.scala
+++ b/akka-actor/src/main/scala/akka/pattern/CircuitBreaker.scala
@@ -155,22 +155,20 @@ class CircuitBreaker(scheduler: Scheduler, maxFailures: Int, callTimeout: Finite
    * The callback is run in the [[scala.concurrent.ExecutionContext]] supplied in the constructor.
    *
    * @param callback Handler to be invoked on state change
-   * @tparam T Type supplied to assist with type inference, otherwise ignored by implementation
    * @return CircuitBreaker for fluent usage
    */
-  def onOpen[T](callback: ⇒ T): CircuitBreaker = {
-    Open.addListener(() ⇒ callback)
-    this
-  }
+  def onOpen(callback: ⇒ Unit): CircuitBreaker = onOpen(new Runnable { def run = callback })
 
   /**
    * Java API for onOpen
    *
    * @param callback Handler to be invoked on state change
-   * @tparam T Type supplied to assist with type inference, otherwise ignored by implementation
    * @return CircuitBreaker for fluent usage
    */
-  def onOpen[T](callback: Callable[T]): CircuitBreaker = onOpen(callback.call)
+  def onOpen(callback: Runnable): CircuitBreaker = {
+    Open addListener callback
+    this
+  }
 
   /**
    * Adds a callback to execute when circuit breaker transitions to half-open
@@ -178,22 +176,20 @@ class CircuitBreaker(scheduler: Scheduler, maxFailures: Int, callTimeout: Finite
    * The callback is run in the [[scala.concurrent.ExecutionContext]] supplied in the constructor.
    *
    * @param callback Handler to be invoked on state change
-   * @tparam T Type supplied to assist with type inference, otherwise ignored by implementation
    * @return CircuitBreaker for fluent usage
    */
-  def onHalfOpen[T](callback: ⇒ T): CircuitBreaker = {
-    HalfOpen.addListener(() ⇒ callback)
-    this
-  }
+  def onHalfOpen(callback: ⇒ Unit): CircuitBreaker = onHalfOpen(new Runnable { def run = callback })
 
   /**
    * JavaAPI for onHalfOpen
    *
    * @param callback Handler to be invoked on state change
-   * @tparam T Type supplied to assist with type inference, otherwise ignored by implementation
    * @return CircuitBreaker for fluent usage
    */
-  def onHalfOpen[T](callback: Callable[T]): CircuitBreaker = onHalfOpen(callback.call)
+  def onHalfOpen(callback: Runnable): CircuitBreaker = {
+    HalfOpen addListener callback
+    this
+  }
 
   /**
    * Adds a callback to execute when circuit breaker state closes
@@ -201,22 +197,20 @@ class CircuitBreaker(scheduler: Scheduler, maxFailures: Int, callTimeout: Finite
    * The callback is run in the [[scala.concurrent.ExecutionContext]] supplied in the constructor.
    *
    * @param callback Handler to be invoked on state change
-   * @tparam T Type supplied to assist with type inference, otherwise ignored by implementation
    * @return CircuitBreaker for fluent usage
    */
-  def onClose[T](callback: ⇒ T): CircuitBreaker = {
-    Closed.addListener(() ⇒ callback)
-    this
-  }
+  def onClose(callback: ⇒ Unit): CircuitBreaker = onClose(new Runnable { def run = callback })
 
   /**
    * JavaAPI for onClose
    *
    * @param callback Handler to be invoked on state change
-   * @tparam T Type supplied to assist with type inference, otherwise ignored by implementation
    * @return CircuitBreaker for fluent usage
    */
-  def onClose[T](callback: Callable[T]): CircuitBreaker = onClose(callback.call)
+  def onClose(callback: Runnable): CircuitBreaker = {
+    Closed addListener callback
+    this
+  }
 
   /**
    * Retrieves current failure count.
@@ -261,7 +255,7 @@ class CircuitBreaker(scheduler: Scheduler, maxFailures: Int, callTimeout: Finite
    * Internal state abstraction
    */
   private sealed trait State {
-    private val listeners = new CopyOnWriteArrayList[() ⇒ _]
+    private val listeners = new CopyOnWriteArrayList[Runnable]
 
     /**
      * Add a listener function which is invoked on state entry
@@ -269,7 +263,7 @@ class CircuitBreaker(scheduler: Scheduler, maxFailures: Int, callTimeout: Finite
      * @param listener listener implementation
      * @tparam T return type of listener, not used - but supplied for type inference purposes
      */
-    def addListener[T](listener: () ⇒ T): Unit = listeners add listener
+    def addListener(listener: Runnable): Unit = listeners add listener
 
     /**
      * Test for whether listeners exist
@@ -288,7 +282,7 @@ class CircuitBreaker(scheduler: Scheduler, maxFailures: Int, callTimeout: Finite
         val iterator = listeners.iterator
         while (iterator.hasNext) {
           val listener = iterator.next
-          executor.execute(new Runnable { def run = listener() })
+          executor.execute(listener)
         }
       }
     }
diff --git a/akka-docs/rst/common/code/docs/circuitbreaker/DangerousJavaActor.java b/akka-docs/rst/common/code/docs/circuitbreaker/DangerousJavaActor.java
index 412e742849..f3347937fc 100644
--- a/akka-docs/rst/common/code/docs/circuitbreaker/DangerousJavaActor.java
+++ b/akka-docs/rst/common/code/docs/circuitbreaker/DangerousJavaActor.java
@@ -29,10 +29,9 @@ public class DangerousJavaActor extends UntypedActor {
     this.breaker = new CircuitBreaker(
       getContext().dispatcher(), getContext().system().scheduler(),
       5, Duration.create(10, "s"), Duration.create(1, "m"))
-      .onOpen(new Callable<Object>() {
-        public Object call() throws Exception {
+      .onOpen(new Runnable() {
+        public void run() {
           notifyMeOnOpen();
-          return null;
         }
       });
   }
diff --git a/akka-docs/rst/java/code/docs/actor/FaultHandlingTestBase.java b/akka-docs/rst/java/code/docs/actor/FaultHandlingTestBase.java
index fdd1937014..c78da61fb1 100644
--- a/akka-docs/rst/java/code/docs/actor/FaultHandlingTestBase.java
+++ b/akka-docs/rst/java/code/docs/actor/FaultHandlingTestBase.java
@@ -7,7 +7,11 @@ package docs.actor;
 import akka.actor.ActorRef;
 import akka.actor.ActorSystem;
 import akka.actor.SupervisorStrategy;
-import static akka.actor.SupervisorStrategy.*;
+import static akka.actor.SupervisorStrategy.resume;
+import static akka.actor.SupervisorStrategy.restart;
+import static akka.actor.SupervisorStrategy.stop;
+import static akka.actor.SupervisorStrategy.escalate;
+import akka.actor.SupervisorStrategy.Directive;
 import akka.actor.OneForOneStrategy;
 import akka.actor.Props;
 import akka.actor.Terminated;
diff --git a/akka-docs/rst/java/code/docs/actor/japi/FaultHandlingDocSample.java b/akka-docs/rst/java/code/docs/actor/japi/FaultHandlingDocSample.java
index f3db04cfdf..5b7a3073c3 100644
--- a/akka-docs/rst/java/code/docs/actor/japi/FaultHandlingDocSample.java
+++ b/akka-docs/rst/java/code/docs/actor/japi/FaultHandlingDocSample.java
@@ -22,7 +22,11 @@ import com.typesafe.config.ConfigFactory;
 
 import static akka.japi.Util.classTag;
 
-import static akka.actor.SupervisorStrategy.*;
+import static akka.actor.SupervisorStrategy.resume;
+import static akka.actor.SupervisorStrategy.restart;
+import static akka.actor.SupervisorStrategy.stop;
+import static akka.actor.SupervisorStrategy.escalate;
+import akka.actor.SupervisorStrategy.Directive;
 import static akka.pattern.Patterns.ask;
 import static akka.pattern.Patterns.pipe;