code: protected boolean addChild(final Widget child,
                                 final GVRSceneObject childRootSceneObject, final int index) {
          return addChild(child, childRootSceneObject, index, false);
      }
docs: Add another {@link Widget} as a child of this one. Convenience method for
  {@link #addChild(Widget, GVRSceneObject, int, boolean) addChild(child, childRootSceneObject,
  index, false)}.
  
  @param child
  The {@code Widget} to add as a child.
  @param childRootSceneObject
  The root {@link GVRSceneObject} of the child.
  @param index
  Position at which to add the child. Pass -1 to add at end.
  @return {@code True} if {@code child} was added; {@code false} if
  {@code child} was previously added to this instance.