docs: public static <T extends Config> T getOrCreate(Factory factory, Object key,
                                                     Class<? extends T> clazz, Map<?, ?>... imports) {
          T existing = get(key);
          if (existing != null) return existing;
          T created = factory.create(clazz, imports);
          T raced = add(key, created);
          return raced != null ? raced : created;
      }