public StateMachineFactory
             <OPERAND, STATE, EVENTTYPE, EVENT>
          addTransition(STATE preState, STATE postState, EVENTTYPE eventType) {
    return addTransition(preState, postState, eventType, null);
  }
@return a NEW StateMachineFactory just like {@code this} with the current
         transition added as a new legal transition.  This overload
         has no hook object.

        Note that the returned StateMachineFactory is a distinct
        object.

        This method is part of the API.

@param preState pre-transition state
@param postState post-transition state
@param eventType stimulus for the transition
ambari-server/src/main/java/org/apache/ambari/server/state/fsm/StateMachineFactory.java