docs: static void unregister(final Object value) {
          Set<IDKey> registry = getRegistry();
          if (registry != null) {
              registry.remove(new IDKey(value));
              synchronized (HashCodeBuilder.class) {
                  //read again
                  registry = getRegistry();
                  if (registry != null && registry.isEmpty()) {
                      REGISTRY.remove();
                  }
              }
          }
      }