title: How to set default selected items in Autocomplete
body: <p>I am using material-ui Autocomplete and I want to add some default selected options to it.</p>
  <p><a href="https://codesandbox.io/s/broken-fire-htxtd?file=/src/App.js" rel="nofollow noreferrer">https://codesandbox.io/s/broken-fire-htxtd?file=/src/App.js</a></p>
  <p>As you can see in the example I am rendering pre-selected items with startAdornment. The problem is when I try to select another item, it automatically deletes the pre-selected items. Also I cannot delete them properly.</p>
  <p>The idea is this default selected to stay selected until I remove them. Also to be able to pick another letter without erasing them.</p>