Add bean validation annotations for the method parameters which are treated as headers

[valery1707]

Bean validation annotations are not generated for the method parameters which are treated as headers.

Resolve #7125

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@nmuesch

[aaronbush]

I ran into a similar issue this week with Request Header validations. Happy to see someone has started to look into it already.

In trying your update to modules/openapi-generator/src/main/resources/JavaSpring/headerParams.mustache I ran into a couple of issues. Hoping you can validate these.

• In the case where a header is set to required: false in specification and the useOptional configuration option is set the template will result in adding @Size/etc. annotations to a java.util.Optional type and at validation runtime an error will occur (in my test case No Validator could be found for constraint 'javax.validation.constraint.Size' validating type 'java.util.Optional....'
• It looks like using beanValidationCore in the updated headerParams.mustache template will miss applying the @Valid and @NotNull which are in the beanValidation.mustache template.

One thing that I tried, which may address the issues, is to change the following section in headerParams.mustache from:

{{#useBeanValidation}}{{>beanValidationCore}}{{/useBeanValidation}}

to:

{{required}}{{#useBeanValidation}}{{>beanValidation}}{{/useBeanValidation}}{{/required}}

This will apply the beanValidation (which includes beanValidationCore) in the case where a field is marked as required.

[valery1707]

Using the {{required}}{{#useBeanValidation}}{{>beanValidation}}{{/useBeanValidation}}{{/required}} will add validation constraints only in the case where a field is marked as required, but validation should be applied even for optional headers.
As I see - the problem exists only in the case required: false and useOptional: true because in this case generated wrapper around validated type.
I will try to fix this case.

[aaronbush]

In the case where the specification of the header has a schema type of object instead of a primitive we will need the @Valid annotation. I am thinking that the beanValidation template (includes the beanValidationCore) will help pick up the @Valid annotation. Not sure if this will break your primitive validations. (I don't expect there is heavy use of headers defined as Objects but it is used and valid in the spec - was actually where I hit this issue.)

I would include a part of the specification that includes a header with object type and ensure @Valid is attached to that. Maybe add to the schema something like this:

        - name: requiredObjectWithStringOfLength
          in: header
          required: true
          schema:
            type: object
            required:
              - aString
            properties:
              aString:
                type: string
                minLength: 32
                maxLength: 32

[DonKeyHot1]

Hi, is there any progress on that pull-request?

[wing328]

@valery1707 can you please resolve the merge conflicts when you've time?

[wing328]

cc @cachescrubber (2022/02) @welshm (2022/02) @MelleD (2022/02) @atextor (2022/02) @manedev79 (2022/02) @javisst (2022/02) @borsch (2022/02) @banlevente (2022/02)

[cowclaw]

I'd love to see this integrated! It would save us having to maintain a customized mustache template for header parameters. Thanks for the PR!

[wing328]

@valery1707 can you please resolve the merge conflicts when you've time?