Algorithm(String algorithmName, HashFunction hashFn) {
      this.algorithmName = algorithmName;
      this.hashFn = hashFn;
    }

    MessageDigest getMessageDigest() {
      try {
        return MessageDigest.getInstance(algorithmName);
      } catch (NoSuchAlgorithmException e) {
        throw new AssertionError(e);
      }
    }

    HashFunction getHashFunction() {
      return hashFn;
    }
  }

   * certificates.
   */
  private SSLSocketFactory defaultSslSocketFactory(X509TrustManager trustManager)
      throws NoSuchAlgorithmException, KeyManagementException {
    SSLContext sslContext = SSLContext.getInstance("TLS");
    sslContext.init(null, new TrustManager[] { trustManager }, null);

    return sslContext.getSocketFactory();
  }

  /** Returns a trust manager that trusts the VM's default certificate authorities. */

  private final Map<TypeToken<? extends @NonNull B>, B> backingMap = new HashMap<>();

  @Override
  public <T extends @NonNull B> @Nullable T getInstance(Class<T> type) {
    return trustedGet(TypeToken.of(type));
  }

  @Override
  public <T extends @NonNull B> @Nullable T getInstance(TypeToken<T> type) {
    return trustedGet(type.rejectTypeVariables());
  }

  @Override
  @CanIgnoreReturnValue

    //                                                                             =======
    @Override
    public ThumbnailQueueDbm asDBMeta() {
        return ThumbnailQueueDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "thumbnail_queue";
    }

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

    //                                                                             =======
    @Override
    public CrawlingInfoDbm asDBMeta() {
        return CrawlingInfoDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "crawling_info";
    }

    @Override
    public boolean hasSpecifiedColumn() {
        return _specification != null;
    }

    //                                                                             =======
    @Override
    public FavoriteLogDbm asDBMeta() {
        return FavoriteLogDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "favorite_log";
    }

    @Override
    public boolean hasSpecifiedColumn() {
        return _specification != null;
    }

    //                                                                             =======
    @Override
    public RoleTypeDbm asDBMeta() {
        return RoleTypeDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "role_type";
    }

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

    //                                                                             =======
    @Override
    public BoostDocumentRuleDbm asDBMeta() {
        return BoostDocumentRuleDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "boost_document_rule";
    }

    @Override
    public boolean hasSpecifiedColumn() {
        return _specification != null;

    //                                                                             =======
    @Override
    public FileAuthenticationDbm asDBMeta() {
        return FileAuthenticationDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "file_authentication";
    }

    @Override
    public boolean hasSpecifiedColumn() {
        return _specification != null;

    //                                                                             =======
    @Override
    public KeyMatchDbm asDBMeta() {
        return KeyMatchDbm.getInstance();
    }

    @Override
    public String asTableDbName() {
        return "key_match";
    }

    @Override
    public boolean hasSpecifiedColumn() {
        return _specification != null;
    }