[BUG] [JavaSpring] apiDelegate.mustache template is missing useBeanValidation imports

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

apiDelegate.mustache is not including useBeanValidation flag, because of that when using validation tags on queryParams compilations fails because bean validation imports are not included

{{#useBeanValidation}}
import javax.validation.constraints.*;
import javax.validation.Valid;
{{/useBeanValidation}}

openapi-generator version

v6.0.0 and current master

OpenAPI declaration file content or url

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/JavaSpring/apiDelegate.mustache

Generation Details

<generatorName>spring</generatorName>
<library>spring-boot</library>
<useBeanValidation>true</useBeanValidation>
<delegatePattern>true</delegatePattern>

Steps to reproduce

Compile a swagger 2.0 spec with validation types in any queryparam

Related issues/PRs

N/A

Suggest a fix

Add useBeanValidation snippet used in https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/JavaSpring/apiController.mustache#L38

{{#useBeanValidation}}
import javax.validation.constraints.*;
import javax.validation.Valid;
{{/useBeanValidation}}

Start with modules/openapi-generator/src/main/resources/JavaSpring/apiDelegate.mustache and compare its imports with apiController.mustache, especially when useBeanValidation is true. Reproduce with the spring generator, spring-boot library, delegatePattern, and a validation type on a query parameter. Done means the generated delegate compiles with the required bean validation imports.