title: What is the difference betweeen "MediaType.APPLICATION_JSON" and "application/json"
body: <p>I am new to Jersey.
  For return type, I would like to know:</p>
  
  <p>What is the difference between <code>application/json</code> and <code>MediaType.APPLICATION_JSON</code>?</p>
  
  <p>What is the right term to put in <code>@Produces()</code>?</p>