Disables nested scroll and, by consequence, the expand/collapse from AppBar. Don't forget to manually expand/collapse app bar in code.

DisableableAppBarLayoutBehavior.java

import android.content.Context;
import android.support.design.widget.AppBarLayout;
import android.support.design.widget.CoordinatorLayout;
import android.util.AttributeSet;
import android.view.View;

public class NestedScrollAppBarBehavior extends AppBarLayout.Behavior {
    private boolean nestedScrollEnabled;

    public DisableableAppBarLayoutBehavior() {
        super();
    }

    public DisableableAppBarLayoutBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void setNestedScrollEnabled(boolean enabled) {
        nestedScrollEnabled = enabled;
    }

    @Override
    public boolean onStartNestedScroll(
            CoordinatorLayout parent,
            AppBarLayout child,
            View directTargetChild,
            View target,
            int nestedScrollAxes) {

        return nestedScrollEnabled && 
                super.onStartNestedScroll(
                        parent, 
                        child, 
                        directTargetChild, 
                        target, 
                        nestedScrollAxes);
    }
}