docs: @Override
      @TargetApi(Build.VERSION_CODES.LOLLIPOP)
      public void getOutline(@NonNull Outline outline) {
          final ChildDrawable[] array = mLayerState.mChildren;
          final int N = mLayerState.mNum;
          for (int i = 0; i < N; i++) {
              final Drawable dr = array[i].mDrawable;
              if (dr != null) {
                  dr.getOutline(outline);
                  if (!outline.isEmpty()) {
                      return;
                  }
              }
          }
      }