title: ant design collapse - open all
body: <p>I'm new to React and Ant Design. Ant design's collapse widget allows all items to be open, but there is no way pre-baked way to set the items to be all open by default - you can only set a single collapse unit to be default opened with</p>
  
  <pre><code>defaultActiveKey={['1']}
  </code></pre>
  
  <p>How would I default open all? </p>