docs: @Nonnull
    @ReturnsMutableCopy
    public ICommonsList <IUserGroup> getAllUserGroupsWithAssignedUser (@Nullable final String sUserID)
    {
      if (StringHelper.hasNoText (sUserID))
        return new CommonsArrayList <> ();
  
      return getAll (aUserGroup -> aUserGroup.containsUserID (sUserID));
    }