docs: @Exported
      public String getBackupVersion() {
          File backup = getBackupFile();
          if (backup.exists()) {
              try {
                  try (JarFile backupPlugin = new JarFile(backup)) {
                      return backupPlugin.getManifest().getMainAttributes().getValue("Plugin-Version");
                  }
              } catch (IOException e) {
                  LOGGER.log(WARNING, "Failed to get backup version from " + backup, e);
                  return null;
              }
          } else {
              return null;
          }
      }