Fix state entry called too many times

- Fix double entry in a case that target is initial state
  and source is target's direct parent.
- Fixes #191

spring-statemachine-core/src/main/java/org/springframework/statemachine/support/AbstractStateMachine.java

@@ -988,6 +988,9 @@ public abstract class AbstractStateMachine<S, E> extends StateMachineObjectSuppo
 			} else if (isComingFromOtherSubmachine) {
 			} else if (!isSubOfSource && !isSubOfTarget && findDeep2 == null) {
 			} else if (isSubOfSource && !isSubOfTarget && currentState == transition.getTarget()) {
+				if (isDirectSubstate(transition.getSource(), transition.getTarget())) {
+					return;
+				}
 			} else if (!isSubOfSource && !isSubOfTarget && (transition.getSource() == currentState && StateMachineUtils.isSubstate(currentState, transition.getTarget()))) {
 			} else if (!isSubOfSource && !isSubOfTarget) {
 				return;
@@ -999,4 +1002,14 @@ public abstract class AbstractStateMachine<S, E> extends StateMachineObjectSuppo
 		state.entry(stateContext);
 	}
 
+	private static <S, E> boolean isDirectSubstate(State<S, E> left, State<S, E> right) {
+		// Checks if right hand side is a direct substate of a left hand side.
+		if (left != null && left.isSubmachineState()) {
+			StateMachine<S, E> submachine = ((AbstractState<S, E>)left).getSubmachine();
+			return submachine.getStates().contains(right);
+		} else {
+			return false;
+		}
+	}
+
 }

spring-statemachine-samples/showcase/src/test/java/demo/showcase/ShowcaseTests.java

@@ -82,6 +82,8 @@ public class ShowcaseTests {
 		assertThat(listener.stateChangedLatch.await(1, TimeUnit.SECONDS), is(true));
 		assertThat(listener.stateEnteredLatch.await(1, TimeUnit.SECONDS), is(true));
 		assertThat(listener.stateExitedLatch.await(1, TimeUnit.SECONDS), is(true));
+		assertThat(listener.statesExited.size(), is(2));
+		assertThat(listener.statesEntered.size(), is(2));
 		assertThat(machine.getState().getIds(), contains(States.S0, States.S1, States.S11));
 	}