docs: private <T> String format(final T t,
                                final IClassContainer container,
                                final Mode mode) {
          final List<ExportContainer> exportContainers = extractExportContainers(t, container);
  
          final String tabObject = (mode == Mode.SINGLE) ? "" : "\t";
  
          final StringBuilder builder = new StringBuilder()
                  .append(tabObject)
                  .append(wrapOpenXmlTag(container.getExportClassName()))
                  .append("\n");
  
          final String resultValues = exportContainers.stream()
                  .map(c -> buildXmlValue(mode, container.getField(c.getExportName()), c))
                  .collect(Collectors.joining("\n"));
  
          builder.append(resultValues)
                  .append("\n");
  
          return builder.append(tabObject)
                  .append(wrapCloseXmlTag(container.getExportClassName()))
                  .toString();
      }