Decommission unused options or options that can be replaced by modifying the templates

Description

Some generators such as Java client generator have too many options: https://github.com/OpenAPITools/openapi-generator/blob/master/docs/generators/java.md (which has like 50 options)

Before the 4.0.x release, we want to review and potentially decommission the "unused" options or options that can be replaced by modifying the templates.

openapi-generator version

4.0.x

Suggest a fix/enhancement

If anyone wants to decommission certain options in a particular generator, please reply below to let us know.