code: protected URI doPostCreate(String path, Object o) throws ClientException {
          return doPostCreate(path, o, null);
      }
docs: Creates a resource specified as a JSON object. Adds appropriate Accepts
  and Content Type headers.
  
  @param path the the API to call.
  @param o the object that will be converted to JSON for sending. Must
  either be a Java bean or be recognized by the object mapper.
  @return the URI representing the created resource, for use in subsequent
  operations on the resource.
  @throws ClientException if a status code other than 201 (Created) is
  returned.