//                                                                           =========
    private static final ThumbnailQueueDbm _instance = new ThumbnailQueueDbm();

    private ThumbnailQueueDbm() {
    }

    public static ThumbnailQueueDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

                  Class<Unsafe> k = Unsafe.class;
                  for (Field f : k.getDeclaredFields()) {
                    f.setAccessible(true);
                    Object x = f.get(null);
                    if (k.isInstance(x)) {
                      return k.cast(x);
                    }
                  }
                  throw new NoSuchFieldError("the Unsafe");
                });
      } catch (PrivilegedActionException e) {

    //                                                                           =========
    private static final RelatedQueryDbm _instance = new RelatedQueryDbm();

    private RelatedQueryDbm() {
    }

    public static RelatedQueryDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final RequestHeaderDbm _instance = new RequestHeaderDbm();

    private RequestHeaderDbm() {
    }

    public static RequestHeaderDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final RoleTypeDbm _instance = new RoleTypeDbm();

    private RoleTypeDbm() {
    }

    public static RoleTypeDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final BoostDocumentRuleDbm _instance = new BoostDocumentRuleDbm();

    private BoostDocumentRuleDbm() {
    }

    public static BoostDocumentRuleDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final DuplicateHostDbm _instance = new DuplicateHostDbm();

    private DuplicateHostDbm() {
    }

    public static DuplicateHostDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final AccessTokenDbm _instance = new AccessTokenDbm();

    private AccessTokenDbm() {
    }

    public static AccessTokenDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final LabelTypeDbm _instance = new LabelTypeDbm();

    private LabelTypeDbm() {
    }

    public static LabelTypeDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

internal fun <T> readFieldOrNull(
  instance: Any,
  fieldType: Class<T>,
  fieldName: String,
): T? {
  var c: Class<*> = instance.javaClass
  while (c != Any::class.java) {
    try {
      val field = c.getDeclaredField(fieldName)
      field.isAccessible = true
      val value = field.get(instance)
      return if (!fieldType.isInstance(value)) null else fieldType.cast(value)