docs: JcrNodeType registerNodeType( NodeTypeDefinition ntd,
                                    boolean failIfNodeTypeExists )
          throws InvalidNodeTypeDefinitionException, NodeTypeExistsException, RepositoryException {
          assert ntd != null;
          List<JcrNodeType> result = registerNodeTypes(Collections.singletonList(ntd), failIfNodeTypeExists, false, true);
          return result.isEmpty() ? null : result.get(0);
      }