docs: @Nonnull
    public IUserGroup createNewUserGroup (@Nonnull @Nonempty final String sName,
                                          @Nullable final String sDescription,
                                          @Nullable final Map <String, String> aCustomAttrs)
    {
      // Create user group
      final UserGroup aUserGroup = new UserGroup (sName, sDescription, aCustomAttrs);
  
      m_aRWLock.writeLocked ( () -> {
        // Store
        internalCreateItem (aUserGroup);
      });
      AuditHelper.onAuditCreateSuccess (UserGroup.OT, aUserGroup.getID (), sName, sDescription, aCustomAttrs);
  
      // Execute callback as the very last action
      m_aCallbacks.forEach (aCB -> aCB.onUserGroupCreated (aUserGroup, false));
  
      return aUserGroup;
  
    }