docs: protected void marshalRuleHeader(final RuleModel model,
                                       final StringBuilder buf) {
          buf.append("rule \"" + marshalRuleName(model) + "\"");
          if (null != model.parentName && model.parentName.length() > 0) {
              buf.append(" extends \"" + model.parentName + "\"\n");
          } else {
              buf.append('\n');
          }
      }