What is equivalent to onPrepareOptionsMenu for the support toolbar?

Question

I know that if I have a v7 support toolbar installed in my Activity, I can make changes to the overflow menu right before displaying it by overriding onPrepareOptionsMenu()

However, I have a separate v7 support toolbar. I still want to display the overflow menu and be able to update it right before it opens. I know how to display it ...

 Toolbar toolbar = ... toolbar.inflateMenu(R.menu.my_menu); toolbar.setOnMenuItemClickListener(new Toolbar.OnMenuItemClickListener() { @Override public boolean onMenuItemClick(MenuItem item) { // TODO return false; } }); 

... but how can I make changes right before the overflow menu opens?