code: @Deprecated
      public KsiBlockSignerBuilder setDefaultHashAlgorithm(HashAlgorithm algorithm) {
          notNull(algorithm, "Hash algorithm");
          algorithm.checkExpiration();
          this.algorithm = algorithm;
          return this;
      }
docs: Sets the hash algorithm used by {@link HashTreeBuilder}.
  @deprecated Use {@link KsiBlockSignerBuilder#setTreeBuilder(TreeBuilder)} instead.