title: GraphQL Java client library
body: <p>I am looking for a java <em>client</em> library for GraphQL. 
  This is to use for server-to-server communication, both in java.
  No android, not javascript... just java.
  Apollo is the nearest answer, and it seems like it is for Android only, not for plain-java applications.
  Lots of examples about build server in java, nothing about client.
  Any idea?
  Thanks!</p>