code: void unregisterEntry(ListIterator<PathElement> iterator, String value, ConcreteNotificationHandlerRegistration.NotificationHandlerEntry entry) {
          NotificationHandlerNodeRegistry registry = childRegistries.get(value);
          if (registry == null) {
              return;
          }
          registry.unregisterEntry(iterator, entry);
      }
docs: Get the registry child for the given {@code elementValue} and traverse it to unregister the entry.