code: @NonNull
      public Transition removeListener(@NonNull TransitionListener listener) {
          if (mListeners == null) {
              return this;
          }
          mListeners.remove(listener);
          if (mListeners.size() == 0) {
              mListeners = null;
          }
          return this;
      }
docs: Removes a listener from the set listening to this animation.
  
  @param listener the listener to be removed from the current set of
  listeners for this transition.
  @return This transition object.