design:23.2.0’以上当把FloatActionBar的anchor写成CoordinatorLayout就会出现异常

    <android.support.design.widget.FloatingActionButton
                android:id="@+id/fab"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_margin="15dp"
                android:src="@drawable/ic_launcher"
                app:layout_anchor="@id/view_pager"
                app:layout_anchorGravity="bottom|right"
                app:layout_behavior="com.xgs.androiddemo.view.FooterBehavior"/>

    @Override
    public void onNestedPreScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull View child, @NonNull View target, int dx, int dy, @NonNull int[] consumed, int type) {
        if (dy > 0 && directionChange < 0 || dy < 0 && directionChange > 0) {
            directionChange = 0;
            child.animate().cancel();
        }
        directionChange += dy;
        if (directionChange > child.getHeight() && child.getVisibility() == View.VISIBLE) {
            hide(child);
        } else if (directionChange < 0 && child.getVisibility() != View.VISIBLE) {
            show(child);
        }
    }

    private void hide(final View view) {
        ViewPropertyAnimator animator = view.animate().translationY(view.getHeight()).setInterpolator(new FastOutSlowInInterpolator()).setDuration(200);
        animator.setListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animator) {
                view.setVisibility(View.INVISIBLE);
            }
        });
        animator.start();
    }