message: Updated prop to allow itemsRef by string
diff: @@ -215,7 +215,14 @@ function baseProp(rawOptions: any, Type: any, target: any, key: string, whatis:
  }
  const itemsRef = rawOptions.itemsRef;
  - if (itemsRef) {
  + if (typeof itemsRef === 'string') {
  + schema[name][key][0] = {
  + ...schema[name][key][0],
  + type: mongoose.Schema.Types.ObjectId,
  + ref: itemsRef,
  + };
  + return;
  + } else if (itemsRef) {
  schema[name][key][0] = {
  ...schema[name][key][0],
  type: mongoose.Schema.Types.ObjectId,
  