docs: public AbstractJcrNode getNonSystemNodeByIdentifier( String id ) throws ItemNotFoundException, RepositoryException {
          checkLive();
          if (NodeKey.isValidFormat(id)) {
              // Try the identifier as a node key ...
              try {
                  NodeKey key = new NodeKey(id);
                  return node(key, null);
              } catch (ItemNotFoundException e) {
                  // continue ...
              }
          }
          // Try as node key identifier ...
          NodeKey key = this.rootNode.key.withId(id);
          return node(key, null);
      }