* Adds v2 spec additionalproperties examples, adds v3 spec nulllable model example, updates samples
* Remaining samples updates
* Adds csharp generator update to handle models with multilevel parent types, which works for the AdditionalPropertiesObject model, samples updated
* fix InlineModelResolver's logis and use openapi-generator's InlineModelResolver, so that nested "required" works correctly
* add "required" to nested model schema
* update ensure-up-to-date to include openapi v3's jaxrs
* change test required field
* fix sample shell script, hide timestamp
* fix NPE
* move test case to petstore-with-fake-endpoints-models-for-testing.yaml
* fix jaxrs-jersey (oas3) example generate shell script to use petstore-with-fake-endpoints-models-for-testing.yaml
* add default value
* re-generate samples
* Run ./bin/utils/ensure-up-to-date to re-generate samples run in the CI.
* Fixed the #1088 issue by removing the update of enumeration properties while processing objects that reference them. Launched the ./bin/csharp-petstore-all.sh script.
