Project(Extend(AggregationJoin(Aggregation(??agg1: ?c, SUM,
                                           {},
                                           G1=Group((?a),
                                              Filter((str(?a)  = "something_that_not_exists"),
                                              BGP( ?a ?b ?c))))),
               ?s,
               ??agg1),
        {?s})