[JavaSpring] Generate bean validation annotations for form parameters

[basduineveld]

When generating a POST endpoint which consumes application/x-www-form-urlencoded with the JavaSpring module, the resulting method in the Api class is missing bean validation annotations such as @NotNull, @Min and @Max. Changing the endpoint to a GET with the same parameters as query parameters leads to a Java method with an identical signature, but then the validation annotations are present.

This PR copies the relevant part of queryParams.mustache to formParams.mustache. The contained beanValidationFormParams.mustache is slightly simpler than the beanValidationQueryParams.mustache, because formParams.mustache does not consider the useOptional flag (I didn't want to add support for that in this PR, as I don't know what the implications are).

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@cachescrubber (2022/02) @welshm (2022/02) @MelleD (2022/02) @atextor (2022/02) @manedev79 (2022/02) @javisst (2022/02) @borsch (2022/02) @banlevente (2022/02) @Zomzog (2022/09) @martin-mfg (2023/08)

Please verify whether this is considered a breaking change according to your definition.

[wing328]

Can you please resolve the merge conflicts when you've time?

[welshm]

Because this could be a breaking change for users of the generator, should this target the next major release?

Code otherwise seems fine

[basduineveld]

@wing328 I've resolved the merge conflicts.
@welshm That's probably the safest option, considering endpoint validation will be stricter (even though these requests would already have been invalid according to the API specification).