JSON partial updates make empty holes

Hi,

I'm working on a similar library for .NET and just wanted to share about some behavior that the library may have ignored.
As described in [JSON spec](https://dev.mysql.com/worklog/task/?id=8132#tabs-8132-4) JSON partial updates may create empty spaces between keys and values. Some users experience the problem starting from [MySQL 8.0.16](https://github.com/shyiko/mysql-binlog-connector-java/pull/288)

Steps to reproduce:
`
UPDATE t1 SET JsonColumn='{"id": 1, "name": "Monica", "types":[1,"123"]}' WHERE Id = 1;
UPDATE t1 SET JsonColumn = JSON_SET(JsonColumn, '$.name', 'Mon') WHERE id = 1;
`

In my lib I solved the problem by using the offsets and advancing the empty holes although not sure whether it's the correct solution