[1.8.x] Removed ForeignObjectRel.get_lookup_constraint() [unused].

        # example custom multicolumn joins currently have no remote field).

        self.field_name = None

    def get_lookup_constraint(self, constraint_class, alias, targets, sources, lookup_type,

                              raw_value):

        return self.field.get_lookup_constraint(constraint_class, alias, targets, sources,

                                                lookup_type, raw_value)

    def get_accessor_name(self, model=None):

        # This method encapsulates the logic that decides what name to give an

        # accessor descriptor that retrieves related many-to-one or