// Request
[
  {
    "type": "item_add",
    "temp_id": "To130797fc18884b149da4c8a8f76e015c",
    "args": {
      "content": "hello",
      "project_id": "1223498556",
      "priority": 1,
      "child_order": 24,
      "due": {
        "date": "2019-05-15T20:00:00",
        "timezone": "Europe/Budapest", ⬅⬅⬅ note timezone filled out here
        "is_recurring": false,
        "string": "May 15 20:00",
        "lang": "en"
      }
    },
    "uuid": "9380379b00c84f6cb3d6783f67a848a9"
  },
  {
    "type": "item_complete",
    "args": {
      "id": "To130797fc18884b149da4c8a8f76e015c",
      "date_completed": "2019-05-15T10:46:29Z"
    },
    "uuid": "f7a554b9444b40429aeee5419cefaef6"
  }
]

// Response
{
  "projects": [],
  "items": [
    {
      "content": "hello",
      "due": {
        "date": "2019-05-15T20:00:00",
        "timezone": null, // ⬅⬅⬅ note null here
        "is_recurring": false,
        "string": "May 15 20:00",
        "lang": "en"
      },
      "checked": true,
      "priority": 1,
      "responsible_uid": null,
      "child_order": 24,
      "day_order": -1,
      "parent_id": null,
      "section_id": null,
      "labels": [],
      "assigned_by_uid": "5210211",
      "sync_id": null,
      "project_id": "1223498556",
      "date_added": "2019-05-15T10:46:33+00:00",
      "date_completed": "2019-05-15T10:46:29+00:00",
      "collapsed": false,
      "in_history": true,
      "id": "3199492756",
      "is_deleted": false
    }
  ],
  "temp_id_mapping": {
    "To130797fc18884b149da4c8a8f76e015c": "3199492756",
    "Reb6b403745aa74e8bbdb541ac2bcb6d87": "2248575572"
  },
  "sync_status": {
    "f7a554b9444b40429aeee5419cefaef6": "ok",
    "9380379b00c84f6cb3d6783f67a848a9": "ok",
    "7ea8b1a540b94cafac1484824a1d6cd2": "ok"
  },
}