[BUG][SPRING] Bug using webflux with router functions, duplicated swagger-ui api doc

Bug Report Checklist

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

Description

I have duplicated endpoints in swagger-ui. all the api is shown twice in
http://localhost:8080/webjars/swagger-ui/index.html
see attached

openapi-generator version

            <groupId>org.openapitools</groupId>
            <artifactId>openapi-generator-maven-plugin</artifactId>
            <version>6.0.0-SNAPSHOT</version>

OpenAPI declaration file content or url

https://github.com/influence160/openapi-generator-springdoc-boot-webflux-fonctionnal-example/blob/master/src/main/resources/springdoc-openapi-spring-boot-2-webflux-functional.openapi.modified.yaml

Generation Details

https://github.com/influence160/openapi-generator-springdoc-boot-webflux-fonctionnal-example/blob/master/pom.xml

                        <generatorName>spring</generatorName>      
                      
                            <openApiNullable>false</openApiNullable>
                            <performBeanValidation>true</performBeanValidation>
                            <library>spring-boot</library>
                            <reactive>true</reactive>

                            <interfaceOnly>true</interfaceOnly>
                            <dateLibrary>java8</dateLibrary>
                            <useSpringController>false</useSpringController>
                            <documentationProvider>springdoc</documentationProvider>
                            <skipDefaultInterface>true</skipDefaultInterface>

Steps to reproduce

i have commited my test project in this location
https://github.com/influence160/openapi-generator-springdoc-boot-webflux-fonctionnal-example

to reproduce : build the project and run the WebfluxFunctionalDemoApplication class and go to http://localhost:8080/webjars/swagger-ui/index.html

note that to create this project i have started from the project from springdocs demo https://github.com/springdoc/springdoc-openapi-demos/tree/master/springdoc-openapi-spring-boot-2-webflux-functional
i have generated the yaml file of that demo project and wanted to recreated it using openapi-generator
i just used the module users in my code and havent used the employees and coffee modules

and because i wanted to have a webflux with routing functions project i had to convert all the Mono<ResponseEntity> to Mono<ServerResponse> using the method https://github.com/influence160/openapi-generator-springdoc-boot-webflux-fonctionnal-example/blob/master/src/main/java/othmen/test/openapigenerator/springdoc/demo/app4/user/Util.java

Suggest a fix

in "modules/openapi-generator/src/main/resources/JavaSpring/api.mustache"

correct this block
{{#swagger2AnnotationLibrary}} @Tag(name = "{{{baseName}}}", description = "the {{{baseName}}} API") {{/swagger2AnnotationLibrary}}

by taking all Tags in the operation of the current class

As an enhacement or another fix we my have to search each tag in the list of {{tags}} and use the description externalDocs of each tag to have the correct values of the attributes description and externalDocs

Example
https://github.com/swagger-api/swagger-core/wiki/Swagger-2.X---Annotations#tag

``
openapi: 3.0.1
tags:

• name: Fourth Tag Full
  description: desc
  externalDocs:
  description: docs desc

``

should generate this

@Tag(name = "Fourth Tag Full", description = "desc class", externalDocs = @ExternalDocumentation(description = "docs desc class"))

Start with modules/openapi-generator/src/main/resources/JavaSpring/api.mustache and compare its generated annotations with the linked WebFlux functional reproduction project. Run WebfluxFunctionalDemoApplication and inspect the Swagger UI at /webjars/swagger-ui/index.html to confirm the duplicated endpoints. Done means the generated API documentation no longer shows each endpoint twice while preserving the intended tag metadata.