docs: private String findMainFileFromBackupSuffix(File searchDir, String backupType) {
  
          final String suffix = "." + backupType + ".xml";
          File[] files = null;
          if (searchDir.exists() && searchDir.isDirectory()) {
              files = searchDir.listFiles(new FilenameFilter() {
                  @Override
                  public boolean accept(File dir, String name) {
                      return name.endsWith(suffix);
                  }
  
              });
          }
  
          if (files == null || files.length == 0) {
              throw ControllerLogger.ROOT_LOGGER.configurationFileNotFound(suffix, searchDir);
          } else if (files.length > 1) {
              throw ControllerLogger.ROOT_LOGGER.ambiguousConfigurationFiles(backupType, searchDir, suffix);
          }
  
          String matchName = files[0].getName();
          if (matchName.equals(suffix)) {
              throw ControllerLogger.ROOT_LOGGER.configurationFileNameNotAllowed(backupType);
          }
          String prefix = matchName.substring(0, matchName.length() - suffix.length());
          return prefix + ".xml";
      }