Null reference to activity as runnable back handler

    private final Handler mHandler;

    private final RecentsModel mRecentTasksModel;

    @Nullable

    private final Runnable mActivityBackCallback;

    private Runnable mActivityBackCallback;

    private final SplitAnimationController mSplitAnimationController;

    private final AppPairsController mAppPairsController;

    private final SplitSelectDataHolder mSplitSelectDataHolder;

    public void onDestroy() {

        mContext = null;

        mActivityBackCallback = null;

    }

    /**