Contacts are represented by <contact_record>:

{
  "contact": {
    "blocked_at": null,         // not null if blocked
    "confirmed_at": null,       // not null if confirmed
    "created_at": "2018-10-14 23:10:10 UTC",
    "updated_at": "2018-10-14 23:10:10 UTC",
    "user": {
      "id": 517,
      "nick": "test_user_2"
    }
  }