code: public AsyncRestBuilder body(String jsonBody) {
          accept(HttpHeaders.Values.APPLICATION_JSON);
          contentType(HttpHeaders.Values.APPLICATION_JSON);
          bodyRaw(jsonBody);
          return this;
      }
docs: Sets the body for the request, assuming it is JSON. This is equivalent to setting
  the {@link #contentType(String) "Content-Type"} to <code>"application/json"</code>
  and then setting the body via {@link #bodyRaw(String)}.
  
  Note that you should avoid calling this for HTTP methods where it makes no sense
  (eg. GET, DELETE), as it won't be ignored for these types of requests.
  
  @param jsonBody the JSON body to use, as a String.