docs: private String toPropertiesString(Group[] groups, String headerName, String projectName) {
          StringBuilder result = new StringBuilder();
  
          result.append(format(header, headerName, projectName));
  
          for (Group group : groups) {
              result.append(group.toString());
          }
  
          result.append(generateFileFooter());
          
          return result.toString();
      }