[REQ][Java][Client][RestClient] Group Parameters as one parameter (useSingleRequestParameter) for Spring RestClient

[Nicklas2751]

Like for java native, okhttp and jersey add the possibility to group all parameters into one (object) when useSingleRequestParameter is set true.

Describe the solution you'd like

A record which is generated when the option is set should do the trick. :)

• [x] And, of course, don't forget to update the options documentation when done.

Describe alternatives you've considered

/

Additional context

Example Solutions: https://github.com/OpenAPITools/openapi-generator/blob/eda4547f151a7b5a8952387fa1cb7974c0a5e5ee/modules/openapi-generator/src/main/resources/Java/libraries/microprofile/api.mustache

https://github.com/OpenAPITools/openapi-generator/blob/eda4547f151a7b5a8952387fa1cb7974c0a5e5ee/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/api.mustache

(I'll create a PR soon. This issue is mainly for me to don't forget it ^^)