code: public void auth() throws DockerException {
  		try {
  			client.resource(restEndpointUrl + "/auth")
  					.header("Content-Type", MediaType.APPLICATION_JSON)
  					.accept(MediaType.APPLICATION_JSON)
  					.post(authConfig());
  		} catch (UniformInterfaceException e) {
  			throw new DockerException(e);
  		}
  	}
docs: Authenticate with the server, useful for checking authentication.