[BUG] [Java Spring OAS3] api.mustache does not import Hidden annotation when oas3 is enabled

Created by: jameswynn

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

When oas3 is enabled, the Hidden annotation should be imported. It is used by ServerWebExchange and Pageable.

openapi-generator version

5.3.1

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  title: Api Documentation
  description: Api Documentation
  termsOfService: urn:tos
  contact: {}
  license:
    name: Apache 2.0
    url: http://www.apache.org/licenses/LICENSE-2.0
  version: '1.0'
paths:
  /thingy:
    get:
      operationId: get
      x-spring-paginated: true
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ResponseList'
components:
  schemas:
    ResponseList:
      type: array
      items:
        $ref: '#/components/schemas/ResponseEntry'
    ResponseEntry:
      type: object
      properties:
        id:
          type: string
          format: uuid
        name:
          type: string

Generation Details

Generator name: spring Library: spring-cloud Config options:

• oas3: true

Generated Code from an API:

import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.Parameter;
import io.swagger.v3.oas.annotations.media.Content;
import io.swagger.v3.oas.annotations.media.Schema;
import io.swagger.v3.oas.annotations.parameters.RequestBody;
import io.swagger.v3.oas.annotations.responses.ApiResponse;
import io.swagger.v3.oas.annotations.security.SecurityRequirement;
import io.swagger.v3.oas.annotations.tags.Tag;

Expected Code from an API:

import io.swagger.v3.oas.annotations.Hidden;
import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.Parameter;
import io.swagger.v3.oas.annotations.media.Content;
import io.swagger.v3.oas.annotations.media.Schema;
import io.swagger.v3.oas.annotations.parameters.RequestBody;
import io.swagger.v3.oas.annotations.responses.ApiResponse;
import io.swagger.v3.oas.annotations.security.SecurityRequirement;
import io.swagger.v3.oas.annotations.tags.Tag;

Suggest a fix

Add a new import statement around line 11 of JavaSpring/api.mustache inside the oas3 block.

import io.swagger.v3.oas.annotations.Hidden;