code: function MUTATE_PROP_x(state, payload, PROP_SUBPROP, conf, propValue) {
      if (!isWhat.isArray(payload))
          payload = [payload];
      var ids = getIdsFromPayload(payload, conf, PROP_SUBPROP);
      if (!checkIdWildcardRatio(ids, PROP_SUBPROP, conf))
          return;
      var lastId = ids.pop();
      var propPathWithoutLast = PROP_SUBPROP.slice(0, -1);
      var pathWithIds = fillinPathWildcards(ids, propPathWithoutLast, state, conf);
      var ref = getDeepRef(state, pathWithIds);
      var newValue = getValueFromPayloadPiece(payload.pop());
      if (isWhat.isObject(newValue))
          newValue.id = lastId;
      if (isWhat.isObject(propValue))
          newValue = merge(propValue, newValue);
      return Vue.set(ref, lastId, newValue);
  }
docs: eslint-disable-next-line