public FieldDescriptor map(MessageType.Field am) {
String defaultValue = am.getDefault();
MessageType.Label label = am.getLabel();
List<Option> options = am.getOptions();
Rule rule = Rule.valueOf(label.name());
return new FieldDescriptor.Builder()
.withName(am.getName())
.withNumber(am.getTag())
.withTypeName(am.getType())