docs: private synchronized HostServerGroupEffect getMappableDomainEffect(PathAddress address, String key,
                                                                         Map<String, Set<String>> map, Resource root) {
          if (requiresMapping) {
              map(root);
              requiresMapping = false;
          }
          Set<String> mapped = map.get(key);
          return mapped != null ? HostServerGroupEffect.forDomain(address, mapped)
                                : HostServerGroupEffect.forUnassignedDomain(address);
      }