Image field mapping

{
  "core": {
    "key": "acf_image_field",
    "name": "ACF Image Field",
    "is_list": false,
    "is_required": false,
    "need_internationalization": false,
    "min_list_length": 1,
    "max_list_length": -1,
    "field_type": "library-asset",
    "source_id": null,
    "source_metadata": "{\"is_custom_post_type_field\": true}",  // It is important to identify source_metadata as custom field
    "order_index": 8,
    "help_text": null,
    "editor_metadata": null
  },
  "allowed_types": ["image"],
  "default_values": null
}