docs: public void setLoop(boolean doLoop, GVRContext gvrContext) {
          if (this.loop != doLoop ) {
              // a change in the loop
              for (GVRNodeAnimation gvrKeyFrameAnimation : gvrKeyFrameAnimations) {
                  if (doLoop) gvrKeyFrameAnimation.setRepeatMode(GVRRepeatMode.REPEATED);
                  else gvrKeyFrameAnimation.setRepeatMode(GVRRepeatMode.ONCE);
              }
              // be sure to start the animations if loop is true
              if ( doLoop ) {
                  for (GVRNodeAnimation gvrKeyFrameAnimation : gvrKeyFrameAnimations) {
                      gvrKeyFrameAnimation.start(gvrContext.getAnimationEngine() );
                  }
              }
              this.loop = doLoop;
          }
      }