@NotNull
  private UserDataHolderBase getOrCreateUserDataHolder() {
    if (internalUserDataOrNull == null) {
      userDataUpdater.compareAndSet(this, null, new UserDataHolderBase());
    }
    //noinspection ConstantConditions
    return internalUserDataOrNull;
  }
@NotNull
  private UserDataHolderBase getOrCreateUserDataHolder()