Return an iterator resource attribute filters configured.

def get_attr_filters(self):
        """Return an iterator resource attribute filters configured.
        """
        for f in self.data.keys():
            if f not in self.multi_attrs:
                continue
            fv = self.data[f]
            if isinstance(fv, dict):
                fv['key'] = f
            else:
                fv = {f: fv}
            vf = ValueFilter(fv)
            vf.annotate = False
            yield vf