Christian Wendt

fix 3711 anyOf/oneOf remove old fields from previous schema

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### Reasons for making this change Fixes #3711 - removing old undefined fields when switching to different oneOf/anyOf schema ### Checklist - [ ] **I'm updating documentation** - [ ]...

anyOf/oneOf keeping undefined property of old option

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### Prerequisites - [X] I have searched the existing issues - [X] I understand that providing a [SSCCE](http://sscce.org/) example is tremendously useful to the maintainers. - [X] I have read...