docs: @NonNull
      public TransitionSet addTransition(@Nullable Transition transition) {
          if (transition != null) {
              addTransitionInternal(transition);
              if (mDuration >= 0) {
                  transition.setDuration(mDuration);
              }
              if (mInterpolator != null) {
                  transition.setInterpolator(mInterpolator);
              }
          }
          return this;
      }