title: graphql_flutter return LazyCacheMap, built_value deserializeWith JSON String, how to make them work together
body: <p><code>graphql_flutter</code> return <code>LazyCacheMap</code>, <code>built_value</code> <code>deserializeWith</code> <code>JSON String</code>,  how to make them work together.</p>
  
  <ol>
  <li>I use <code>graphql_flutter</code> to fetch data, and response give the result data as <code>LazyCacheMap</code>.</li>
  <li>And using <code>built_value</code> for data model &amp; data serialization, but since <code>deserializeWith</code> working with <code>JSON String</code>.</li>
  </ol>
  
  <p>What's the best way to work with them together ?</p>
  
  <ul>
  <li>Should I just convert <code>LazyCacheMap</code>'s data of to <code>String</code> and call  <code>deserializeWith</code> ?</li>
  <li>should I use other serialization pubs ?</li>
  </ul>