Attendee's other property is lost after update

[dixonsiu]

Some property is not changeable, so it seems that it is not overwritten. However, at least the following are lost when engine script update the data.

API propery:

    {
      "email": "hoge@gmail.com",
      "displayName": "hoge"
    }

Google data (Before):

  {
   "email": "hoge@gmail.com",
   "displayName": "hoge",
   "optional": true,
   "responseStatus": "needsAction"
  }

Google data (After):

  {
   "email": "hoge@gmail.com",
   "displayName": "hoge",
   "responseStatus": "needsAction"
  }

[shimono]

Let us stop the support for editing attendees on Personium Calendar.