mention stateName in FSM unhandled messages, see #2617

akka-actor/src/main/scala/akka/actor/FSM.scala

@@ -427,6 +427,8 @@ trait FSM[S, D] extends Listeners with ActorLogging {
   /**
    * Set handler which is called upon reception of unhandled messages. Calling
    * this method again will overwrite the previous contents.
+   *
+   * The current state may be queried using ``stateName``.
    */
   final def whenUnhandled(stateFunction: StateFunction): Unit =
     handleEvent = stateFunction orElse handleEventDefault

akka-docs/rst/scala/fsm.rst

@@ -192,6 +192,9 @@ do something else in this case you can specify that with
 .. includecode:: code/docs/actor/FSMDocSpec.scala
    :include: unhandled-syntax
 
+Within this handler the state of the FSM may be queried using the
+:meth:`stateName` method.
+
 **IMPORTANT**: This handler is not stacked, meaning that each invocation of
 :func:`whenUnhandled` replaces the previously installed handler.