code: @Override
    public Service get() {
      String serviceName = this.environment.getVariable(SERVICE_NAME_KEY);
      if (Strings.isNullOrEmpty(serviceName)) {
        String errorMessage =
            String.format("Environment variable '%s' is not set", SERVICE_NAME_KEY);
        throw new IllegalArgumentException(errorMessage);
      }
      String serviceVersion = this.environment.getVariable(SERVICE_VERSION_KEY);
  
      return fetch(serviceName, serviceVersion);
    }
docs: Fetches the service configuration using the service name and the service
  version read from the environment variables.
  
  @return a {@link Service} object generated by the JSON response from Google
  Service Management.