code: public static Request newPostRequest(Session session, String graphPath, GraphObject graphObject, Callback callback) {
          Request request = new Request(session, graphPath, null, HttpMethod.POST , callback);
          request.setGraphObject(graphObject);
          return request;
      }
docs: Creates a new Request configured to post a GraphObject to a particular graph path, to either create or update the
  object at that path.
  
  @param session
  the Session to use, or null; if non-null, the session must be in an opened state
  @param graphPath
  the graph path to retrieve, create, or delete
  @param graphObject
  the GraphObject to create or update
  @param callback
  a callback that will be called when the request is completed to handle success or error conditions
  @return a Request that is ready to execute