How to detect nested fields delete?

Hi, Please help to guide me how to detect value in nested had delete as following case with Kafka connector.

{"_id":"10059872",
"reviews":[{"_id":"AAA"},
		   {"_id":"BBB"},
		   {"_id":"CCC"}
		   ]
}

{"_id":"10059872",
"reviews":[{"_id":"AAA"},
		   {"_id":"CCC"}
		   ]
}

I would like to know “_id”:“10059872” had deleted review “_id”:“BBB”.

How to detect that?