Behavior.java

    @Override
    public boolean onNestedFling(final CoordinatorLayout coordinatorLayout, final AppBarLayout child, View target, float velocityX, final float velocityY, boolean consumed) {
        if (target instanceof RecyclerView && velocityY < 0) {
            final RecyclerView recyclerView = (RecyclerView) target;
            final long start = System.currentTimeMillis();
            recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
                @Override
                public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                    if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                        recyclerView.removeOnScrollListener(this);
                        final View firstChild = recyclerView.getChildAt(0);
                        final int childAdapterPosition = recyclerView.getChildAdapterPosition(firstChild);
                        final long end = System.currentTimeMillis();
                        long dT = end - start;
                        if (childAdapterPosition == 0)
                            fling(coordinatorLayout, child, -child.getTotalScrollRange(), 0, Cv(dT) * Math.abs(velocityY));
                    }
                }
            });
        }
        return super.onNestedFling(coordinatorLayout, child, target, velocityX, velocityY, true);
    }