title: Programmatically collapse or expand CollapsingToolbarLayout
body: <p>Simple question, but I can't find an answer. How can I collapse or expand the <code>CollapsingToolbarLayout</code> programmatically?</p>
  
  <p><img src="https://i.stack.imgur.com/rSzUr.png" alt="collapsed toolbar"></p>
  
  <p>↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓</p>
  
  <p><img src="https://i.stack.imgur.com/AMDbK.png" alt="expanded toolbar"></p>