!act,sam #3889 Adding Activator template FSM/become for Java with Lambda support

* Dining Hakkers Activator template for FSM and become
* Cleaup of FSM event matchers to be more usable and consistent

akka-docs/rst/experimental/index.rst

@@ -21,6 +21,8 @@ prior deprecation.
 
    ../scala/persistence
    ../dev/multi-node-testing
+   ../java/lambda-actors
+   ../java/lambda-fsm
 
 Another reason for marking a module as experimental is that it's too early
 to tell if the module has a maintainer that can take the responsibility

akka-docs/rst/java/lambda-actors.rst

@@ -17,6 +17,13 @@ its syntax from Erlang.
 
 .. _Actor Model: http://en.wikipedia.org/wiki/Actor_model
 
+.. warning::
+
+  The Java with lambda support part of Akka is marked as **“experimental”** as of its introduction in
+  Akka 2.3.0. We will continue to improve this API based on our users’ feedback, which implies that
+  while we try to keep incompatible changes to a minimum, but the binary compatibility guarantee for
+  maintenance releases does not apply to the :class:`akka.actor.AbstractActor`, related classes and
+  the :class:`akka.japi.pf` package.
 
 Creating Actors
 ===============

akka-docs/rst/java/lambda-fsm.rst

@@ -21,6 +21,14 @@ These relations are interpreted as meaning:
   *If we are in state S and the event E occurs, we should perform the actions A
   and make a transition to the state S'.*
 
+.. warning::
+
+  The Java with lambda support part of Akka is marked as **“experimental”** as of its introduction in
+  Akka 2.3.0. We will continue to improve this API based on our users’ feedback, which implies that
+  while we try to keep incompatible changes to a minimum, but the binary compatibility guarantee for
+  maintenance releases does not apply to the :class:`akka.actor.AbstractFSM`, related classes and the
+  :class:`akka.japi.pf` package.
+
 A Simple Example
 ================