Returns a dict expressing the flow match.

def to_jsondict(self):
        """
        Returns a dict expressing the flow match.
        """
        body = {"oxm_fields": [ofproto.oxm_to_jsondict(k, uv) for k, uv
                               in self._fields2],
                "length": self.length,
                "type": self.type}
        return {self.__class__.__name__: body}