Wrong json_encode

[TrickyC94]

You have declared the AuditLog's field "diff" as "json_array" type, for which doctrine handles the conversion automatically.
In AuditSubscriber you convert to json the diff data (here and here) and the result in the database is that we have data encoded twice (in my case the second conversion applies a \ before every ") and when we try to retrieve the data using getDiff() we've the data as a json and not as array.
We are doing something wrong?

We're using Symfony 3.4 with doctrine/dbal 2.5

Update
We've seen pull request #51, and we think that it might've been implemented by mistake (probably it was an encoding issue on Mopster's side, since doctrine's json and json_array type require UTF-8 encoding on the DB's column).