[BUG] [JAVA] spring server returns application/json String without quotes (invalid json)

[davidmoten]

Description

When using spring server generated by openapi-generator-maven-plugin (plugin xml further below), we have a method that returns a simple json string. The problem is that the String reponse of abc should be returned by the server as "abc" but is missing the quotes, thus is invalid json, and the client side fails to process it (especially as the returned Content-Type is application-json, just as declared in api yaml).

Here is a fragment from the generated interface:

    /**
     * GET /jsonString
     *
     * @return ok response (status code 200)
     */
    @Operation(
        operationId = "jsonStringGet",
        responses = {
            @ApiResponse(responseCode = "200", description = "ok response", content = {
                @Content(mediaType = "application/json", schema = @Schema(implementation = String.class))
            })
        }
    )
    @RequestMapping(
        method = RequestMethod.GET,
        value = "/jsonString",
        produces = { "application/json" }
    )
    default ResponseEntity<String> jsonStringGet(
        
    ) {
        return getDelegate().jsonStringGet();
    }

I assume the generated code could be improved for this case so that perhaps the method returned ResponseEntity<StringValue> where the property inside StringValue is annotated with @JsonValue.

openapi-generator version

6.5.0

OpenAPI declaration file content or url

openapi: 3.0.0
info:
    
  title: path tests
  version: v0.1

paths:
          
  /jsonString:
    get:
      responses:
        '200':    
          description: ok response
          content:
            application/json:
              schema: 
                $ref: '#/components/schemas/Name'
             
components:
  schemas:
    Name:
      type: string

Steps to reproduce

Maven plugin fragment that points at above yml:

            <plugin>
                <groupId>org.openapitools</groupId>
                <artifactId>openapi-generator-maven-plugin</artifactId>
                <version>6.5.0</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <inputSpec>${project.basedir}/src/main/openapi/demo.yml</inputSpec>
                            <generatorName>spring</generatorName>
                            <apiPackage>demo.api</apiPackage>
                            <modelPackage>demo.model</modelPackage>
                            <invokerPackage>demo.client</invokerPackage>
                            <configOptions>
                                <delegatePattern>true</delegatePattern>
                            </configOptions>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

[zuston]

How about using JSON.toJSONString to wrap the string

[davidmoten]

How about using JSON.toJSONString to wrap the string

Good suggestion for a workaround but I want the generated service to do the right thing in the first place.