title: Google recaptcha V2 supported content types
body: <p>When querying the state of the "I'm not a robot" user challenge, you have to make a POST request to <code>https://www.google.com/recaptcha/api/siteverify</code> passing your secret key and the response token to know the result of the challenge. But it is undocumented which <code>Content-Type</code>s (MIME types) are supported. I guess every common MIME type is supported (application/x-www-form-urlenconded, application/json, application/xml), but, just for curiosity, </p>
  
  <ul>
  <li>Which are the <code>Content-Type</code>s supported by <code>siteverify</code>?</li>
  <li>Or is that "supported mime types" list for POST request standarized somehow?</li>
  </ul>