Add optional parameter for request body

[MelleD]

The PR set not required request body as Optionals for Spring.
Spring supports Optional for request body same like in DTOs or in QueryParams.
This is a breaking change that is not backwards compatible.

Fix #16971

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[wing328]

This is a breaking change that is not backwards compatible.

Thanks for the PR. Shall we consider this a bug fix instead?

[wing328]

Not related to this PR but can you have a quick look at #16945 when you've time? Thanks.

[MelleD]

Thanks for the PR. Shall we consider this a bug fix instead?

Yes why not I have no strong opinion on that :)

[MelleD]

#16945

I looked into this PR. We currently not using this stubs and interfaces. So not much experience on that.

We use interface only with spring-cloud

[wing328]

We use interface only with spring-cloud

With that PR, my guess is that you don't need the interfaceOnly option any more, right?