in src/main/java/com/googlesource/gerrit/plugins/auditsl4j/AuditRendererToCsv.java [143:151]
  public static <T> String getFieldAsCsv(T result) {
    if (result == null) return "";
    @SuppressWarnings("unchecked")
    CsvFieldFormatter<T> fmt = (CsvFieldFormatter<T>) FIELD_CSV_FORMATTERS.get(result.getClass());
    if (fmt == null) return result.toString();
    return fmt.formatToCsv(result);
  }