message: serialization.json.SerializerOut: Create an empty object if held options are null.
diff: @@ -295,6 +295,9 @@ namespace elle
  {
  if (filled)
  f();
  + // Create an empty object if held options are null.
  + else if (this->_current.back()->type() == typeid(void))
  + *this->_current.back() = elle::json::Object();
  }
  void
  