docs: private static MessageElement getMapKVMessageElements(String name, MapType mapType) {
          MessageElement.Builder ret = MessageElement.builder();
          ret.name(name);
  
          DataType keyType = mapType.keyType();
          Builder fieldBuilder = FieldElement.builder().name("key").tag(1);
          fieldBuilder.type(keyType).label(FieldElement.Label.OPTIONAL);
          ret.addField(fieldBuilder.build());
  
          DataType valueType = mapType.valueType();
          fieldBuilder = FieldElement.builder().name("value").tag(2);
          fieldBuilder.type(valueType).label(FieldElement.Label.OPTIONAL);
          ret.addField(fieldBuilder.build());
  
          return ret.build();
      }