docs: public void start() {
          if (TransitionConfig.isDebug()) {
              getTransitionStateHolder().start();
          }
  
          mLastProgress = Float.MIN_VALUE;
  
          TransitionController transitionController;
          for (int i = 0, size = mTransitionControls.size(); i < size; i++) {
              transitionController = mTransitionControls.get(i);
              if (mInterpolator != null) {
                  transitionController.setInterpolator(mInterpolator);
              }
              //required for ViewPager transitions to work
              if (mTarget != null) {
                  transitionController.setTarget(mTarget);
              }
              transitionController.setUpdateStateAfterUpdateProgress(mUpdateStateAfterUpdateProgress);
              transitionController.start();
          }
      }