code: public com.google.protobuf.ByteString
        getRuleIdBytes() {
      java.lang.Object ref = ruleId_;
      if (ref instanceof java.lang.String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (java.lang.String) ref);
        ruleId_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
docs: <pre>
  Gives the rule an unique ID that can be used for extending in other rules
  through 'extends'. An example of ID is 'closure:innerHtml'.
  </pre>
  
  <code>optional string rule_id = 9;</code>