docs: 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