i can't get object in fileds, how do i get i to make a message notif in android

Question

objects in fields can change their data, I want to retrieve data in the field object to be used as a message. i use RxJava and retrofit.

{
    "status": 422,
    "success": false,
    "error": {
        "code": "validation_failed",
        "message": "The given data failed to pass validation.",
        "fields": {
            "reason": [
                "The reason must be at least 8 characters."
            ],
            "current_password": [
                "The current password you have entered is incorrect."
            ]
        }
    }
}

i wish someone can help me