code: public void setControllerModel(GVRSceneObject controllerModel)
      {
          if (mControllerModel != null)
          {
              mControllerGroup.removeChildObject(mControllerModel);
          }
          mControllerModel = controllerModel;
          mControllerGroup.addChildObject(mControllerModel);
          mControllerModel.setEnable(mShowControllerModel);
      }
docs: Replaces the model used to depict the controller in the scene.
  
  @param controllerModel root of hierarchy to use for controller model
  @see #getControllerModel()
  @see #showControllerModel(boolean)