code: public com.google.protobuf.ByteString
        getMetricBytes() {
      java.lang.Object ref = metric_;
      if (ref instanceof java.lang.String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (java.lang.String) ref);
        metric_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
docs: <pre>
  The name of the metric this quota limit applies to. The quota limits with
  the same metric will be checked together during runtime. The metric must be
  defined within the service config.
  </pre>
  
  <code>string metric = 8;</code>