  void setDynamicMetadata(const std::string& name, const ProtobufWkt::Struct& value) override {
    (*metadata_.mutable_filter_metadata())[name].MergeFrom(value);
  };
  void setDynamicMetadata(const std::string& name, const ProtobufWkt::Struct& value) override {
    (*metadata_.mutable_filter_metadata())[name].MergeFrom(value);
  };