docs: private void addReferences(ModelNode feature, ImmutableManagementResourceRegistration registration) {
          PathAddress address = registration.getPathAddress();
          if (address == null || PathAddress.EMPTY_ADDRESS.equals(address)) {
              return;
          }
          ModelNode refs = feature.get(REFS).setEmptyList();
          if (registration.getParent() != null && registration.getParent().isFeature()) {
              addReference(refs, registration.getParent());
          }
          PathElement element = registration.getPathAddress().getLastElement();
          if (SUBSYSTEM.equals(element.getKey())) {
              ModelNode ref = new ModelNode();
              final String rootType = registration.getPathAddress().getElement(0).getKey();
              if (HOST.equals(rootType)) {
                  ref.get(FEATURE).set(HOST_EXTENSION);
              } else if (PROFILE.equals(rootType)) {
                  ref.get(FEATURE).set(DOMAIN_EXTENSION);
              } else {
                  ref.get(FEATURE).set(EXTENSION);
              }
              ref.get(INCLUDE).set(true);
              refs.add(ref);
          }
          if (refs.asList().isEmpty()) {
              feature.remove(REFS);
          }
      }