* add validJsonObject method

* add check for null

* fix list model generation

* fix optional fields validation

* add tests

* fix variable naming

* update tests

* add fromJson in oneOf, add tests

* convert JSON to static

* remove trailing space

* add fromString methods to all models

* add toJson, fix anyOf template

* remove workarounds

* undo changes to tests

* skip file schema test

* add new file