anchor.diff:  * The `op` field value is now `d`, signifying that this document was deleted
   * The `patch` field does not appear
   * The `after` field does not appear
  +* The `filter` field appears and has the stringified JSON representation of the MongoDB selection criteria used for the delete
   * The `source` field structure has the same fields as before, but the values are different since this event is from a different position in the oplog
   * The `ts_ms` shows the timestamp that {prodname} processed this event
   
  
positive.code:           "name": "io.debezium.data.Json",
            "version": 1,
            "field": "patch"
          },
          {
            "type": "struct",
  
negative.code: 
  * The `op` field value is now `u`, signifying that this document changed because of an update
  * The `patch` field appears and has the stringified JSON representation of the actual MongoDB idempotent change to the document, which in this example involves setting the `first_name` field to a new value
  * The `filter` field appears and has the stringified JSON representation of the MongoDB selection criteria used for the update
  * The `after` field no longer appears
  * The `source` field structure has the same fields as before, but the values are different since this event is from a different position in the oplog
  * The `ts_ms` shows the timestamp that {prodname} processed this event
  