[BUG][Java][Spring] delegate pattern in combination with response wrapper generate code without delegate

Bug Report Checklist

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

Description

openapi-generator version

1. 6.6.0
2. 7.1.0
3. 7.2.0-SNAPSHOT

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  title: Bug Report
  version: 1.0.0
servers:
  - url: /api/v1
paths:
  /bug:
    get:
      summary: Simple method
      operationId: getBug
      responses:
        200:
          description: "OK"
          content:
            'application/json':
              schema:
                type: string

Generation Details

Maven configuration

            <plugin>
                <groupId>org.openapitools</groupId>
                <artifactId>openapi-generator-maven-plugin</artifactId>
                <version>7.1.0</version>
                <executions>
                    <execution>
                        <id>Generate sample</id>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <inputSpec>${project.basedir}/src/main/resources/spec/sample.yml</inputSpec>
                            <apiPackage>com.sample.rest</apiPackage>
                            <modelPackage>com.sample.rest</modelPackage>
                            <generatorName>spring</generatorName>
                            <configOptions>
                                <sourceFolder>java</sourceFolder>
                                <dateLibrary>java8</dateLibrary>
                                <interfaceOnly>true</interfaceOnly>
                                <delegatePattern>true</delegatePattern>
                                <responseWrapper>DeferredResult</responseWrapper>
                            </configOptions>
                            <library>spring-boot</library>
                            <output>${project.build.directory}/generated-sources/server</output>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

Steps to reproduce

1. Generate code
2. Correct code with delegate is expected, here is what I got:

@Generated(value = "org.openapitools.codegen.languages.SpringCodegen", date = "2023-11-30T11:16:24.335072+01:00[Europe/Vienna]")
@Validated
@Tag(name = "bug", description = "the bug API")
public interface BugApi {

    /**
     * GET /bug : Simple method
     *
     * @return OK (status code 200)
     */
    @Operation(
        operationId = "getBug",
        summary = "Simple method",
        responses = {
            @ApiResponse(responseCode = "200", description = "OK", content = {
                @Content(mediaType = "application/json", schema = @Schema(implementation = String.class))
            })
        }
    )
    @RequestMapping(
        method = RequestMethod.GET,
        value = "/bug",
        produces = { "application/json" }
    )
    
    org.springframework.web.context.request.async.DeferredResult<ResponseEntity<String>> _getBug(
        
    );
}

Expected result:

@Generated(value = "org.openapitools.codegen.languages.SpringCodegen", date = "2023-11-30T11:16:24.335072+01:00[Europe/Vienna]")
@Validated
@Tag(name = "bug", description = "the bug API")
public interface BugApi {

    /**
     * GET /bug : Simple method
     *
     * @return OK (status code 200)
     */
    @Operation(
        operationId = "getBug",
        summary = "Simple method",
        responses = {
            @ApiResponse(responseCode = "200", description = "OK", content = {
                @Content(mediaType = "application/json", schema = @Schema(implementation = String.class))
            })
        }
    )
    @RequestMapping(
        method = RequestMethod.GET,
        value = "/bug",
        produces = { "application/json" }
    )
    
    default org.springframework.web.context.request.async.DeferredResult<ResponseEntity<String>> _getBug() {
        return getBug();
    }

    default org.springframework.web.context.request.async.DeferredResult<ResponseEntity<String>> getBug() {
        org.springframework.web.context.request.async.DeferredResult<ResponseEntity<String>> result =
                new org.springframework.web.context.request.async.DeferredResult<ResponseEntity<String>>();
        result.setResult(ResponseEntity.status(HttpStatus.NOT_IMPLEMENTED).build());
        return result;
    }
}

Related issues/PRs

Suggest a fix

Start with the supplied OpenAPI declaration and Maven plugin configuration, generating the spring generator with the spring-boot library, interfaceOnly, delegatePattern, and DeferredResult responseWrapper options. Compare the generated BugApi interface with the expected output; done means the delegate methods and response wrapper are generated together without losing the delegate implementation.