* add spring support for SSE conform specs
see https://github.com/OpenAPITools/openapi-generator/issues/6123 for the ongoing discussion
* extend generator option documentation
* applied review suggestions
* regenerated samples
* regenerated docu
* fix code style: removed tabs
* add nullable case to spring test spec
* generate samples for changed spring input
* add nullable case to general test spec
* generate samples for changed general input
* generate samples again
* generates samples again
* re-build from new sources, generates samples again