// mapper for member field
        if ( e.getMembers() != null ) {

            e.getMembers().clear();
            // may add null to target collection, check s.getMembers() != null is what I expected
            e.getMembers().addAll( projMemberDTOListToProjCoreUserEntityList( s.getMembers() ) );
        }

        else {

            e.setMembers( projMemberDTOListToProjCoreUserEntityList( s.getMembers() ) );
        }

// mapper source collection
    protected List<ProjCoreUserEntity> projMemberDTOListToProjCoreUserEntityList(List<ProjMemberDTO> list) {

        if ( list == null ) {

            return null;
        }

        List<ProjCoreUserEntity> list_ = new ArrayList<ProjCoreUserEntity>();

        for ( ProjMemberDTO projMemberDTO : list ) {

            list_.add( map( projMemberDTO ) );
        }

        return list_;
    }