public function assertResponseBodyIsAnEmptyJsonObject() {
        $this->requireResponse();
        $body = $this->getResponseBody();

        try {
            Assertion::isInstanceOf($body, 'stdClass', 'Expected response body to be a JSON object.');
            Assertion::same('{}', $encoded = json_encode($body, JSON_PRETTY_PRINT), sprintf(
                'Expected response body to be an empty JSON object, got "%s".',
                $encoded
            ));
        } catch (AssertionFailure $e) {
            throw new AssertionFailedException($e->getMessage());
        }
    }