Setting custom json_encoder and json_decoder classes on the app or a blueprint, and the corresponding json.JSONEncoder and JSONDecoder classes, are deprecated. JSON behavior can now be overridden using the app.json provider interface. https://github.com/pallets/flask/pull/4692
Change Description
Updates Flask JSON interfaces to the newer pattern.
Rationale
Flask deprecated and removed the older way of doing things. See https://github.com/nasa/fprime/issues/2077
From Flask release notes: