code: public void setTransition(@NonNull Scene fromScene, @NonNull Scene toScene, @Nullable Transition transition) {
          ArrayMap<Scene, Transition> sceneTransitionMap = mScenePairTransitions.get(toScene);
          if (sceneTransitionMap == null) {
              sceneTransitionMap = new ArrayMap<Scene, Transition>();
              mScenePairTransitions.put(toScene, sceneTransitionMap);
          }
          sceneTransitionMap.put(fromScene, transition);
      }
docs: Sets a specific transition to occur when the given pair of scenes is
  exited/entered.
  
  @param fromScene  The scene being exited when the given transition will
  be run
  @param toScene    The scene being entered when the given transition will
  be run
  @param transition The transition that will play when the given scene is
  entered. A value of null will result in the default behavior of
  using the default transition instead.