title: Add authentication in elasticsearch high level client for Java
body: <p>I am using an elasticsearch instance in elastic cloud instance secured with X-PACK.</p>
  <p>I had been using the high level rest client before without any problems but I am unable to find how to send the basic authentication header on it.</p>
  <p>I have tried to put the credentials as part of the URL but it didn't seem to be able to connect in that case.</p>
  <p>Has anyone succeed to connect to a secured elasticsearch with high level rest client?</p>