code: def _GenOpenApiSpec(service_class_names, output_path, hostname=None,
                      application_path=None, x_google_api_name=False):
    
    output_files = []
    service_configs = GenApiConfig(
        service_class_names, hostname=hostname,
        config_string_generator=openapi_generator.OpenApiGenerator(),
        application_path=application_path,
        x_google_api_name=x_google_api_name)
    for api_name_version, config in service_configs.iteritems():
      openapi_name = api_name_version.replace('-', '') + 'openapi.json'
      output_files.append(_WriteFile(output_path, openapi_name, config))
  
    return output_files
docs: Write openapi documents generated from the service classes to file.
  
    Args:
      service_class_names: A list of fully qualified ProtoRPC service names.
      output_path: The directory to which to output the OpenAPI specs.
      hostname: A string hostname which will be used as the default version
        hostname. If no hostname is specified in the @endpoints.api decorator,
        this value is the fallback. Defaults to None.
      application_path: A string containing the path to the AppEngine app.
  
    Returns:
      A list of OpenAPI spec filenames.