protected final Map<String, PropertyGateway> _epgMap = newHashMap();
    {
        setupEpg(_epgMap, et -> ((BoostDocumentRule) et).getBoostExpr(),
                (et, vl) -> ((BoostDocumentRule) et).setBoostExpr(DfTypeUtil.toString(vl)), "boostExpr");
        setupEpg(_epgMap, et -> ((BoostDocumentRule) et).getCreatedBy(),
                (et, vl) -> ((BoostDocumentRule) et).setCreatedBy(DfTypeUtil.toString(vl)), "createdBy");