private ReferenceJoin addJoinLink(FilterLevel filterLevel, JoinNode node) { Slot<ForeignKey> foreignKey = addForeignKey(filterLevel, node); Slot<PrimaryKeyMap> primaryKey = addPrimaryKey(filterLevel, node.getRightFormId()); ReferenceJoinKey referenceJoinKey = new ReferenceJoinKey(filterLevel, foreignKey, primaryKey); ReferenceJoin joinLink = joinLinks.get(referenceJoinKey); if(joinLink == null) { joinLink = new ReferenceJoin(foreignKey, primaryKey, node.toString()); joinLinks.put(referenceJoinKey, joinLink); } return joinLink; }