overview image links are missing type

there is type missing in this json:

 {
                    "id": 96,
                    "linkedOverviewImage": 26,
                    "polygon": [
                        {
                            "x": 4852.0,
                            "y": 107.0
                        },
                        {
                            "x": 5125.0,
                            "y": 107.0
                        },
                        {
                            "x": 5125.0,
                            "y": 245.0
                        },
                        {
                            "x": 4852.0,
                            "y": 245.0
                        }
                    ]
                },