def pretty_print_config_to_json(self, services, hostname=None, x_google_api_name=False):
    """JSON string description of a protorpc.remote.Service in OpenAPI format.

    Args:
      services: Either a single protorpc.remote.Service or a list of them
        that implements an api/version.
      hostname: string, Hostname of the API, to override the value set on the
        current service. Defaults to None.

    Returns:
      string, The OpenAPI descriptor document as a JSON string.
    """
    descriptor = self.get_openapi_dict(services, hostname, x_google_api_name=x_google_api_name)
    return json.dumps(descriptor, sort_keys=True, indent=2,
                      separators=(',', ': '))