code: @RequiresApi(Build.VERSION_CODES.KITKAT)
      @NonNull
      public IconicsAnimationProcessor addPauseListener(@NonNull IconicsAnimationPauseListener listener) {
          if (mPauseListeners == null) {
              mPauseListeners = new ArrayList<>();
              if (mProxyPauseListener == null) {
                  initProxyPauseListener();
              }
              mAnimator.addPauseListener((Animator.AnimatorPauseListener) mProxyPauseListener);
          }
          mPauseListeners.add(listener);
          return this;
      }
docs: Adds a pause listener to this processor.
  
  @param listener the listener to be added to the current set of pause listeners
  for this processor.