How to add an example in @ApiResponse with Swagger?

Question

I would like to add an example with Swagger in my method, I have tried a few things, but they didn't work.

I have my Interface, when I define the method:

@Api(value = "test API")
@RequestMapping("/api/v1/product")
public interface TestController {

    @ApiOperation(
            value = "Service that return a Product",
            notes = "This service returns a Product by the ID",
            nickname = "getProductById",
            response = ProductResponse.class)
    @ApiResponses(value = {
            @ApiResponse(code = 200, message = "The request has succeeded.", response = ProductResponse.class),
            @ApiResponse(code = 500, message = "Internal server error.", response = ProductResponse.class) })
    @GetMapping(
            value = "/productById",
            produces = { "application/json" }
    )
    ResponseEntity<ProductResponse> getProductById(@RequestParam(value = "productId", required = true) String productId);

The ProductResponse class is the following:

@Getter
@Setter
@AllArgsConstructor
public class ProductResponse {

    private Product product;
    private CustomException customException;

}

The Product class is the following:

@Getter
@Setter
@AllArgsConstructor
public class Product {

    @JsonProperty("id")
    private String id;

    @JsonProperty("productName")
    private String productName;

    @JsonProperty("productDescription")
    private String productDescription;

    @JsonProperty("unitPrice")
    private Double unitPrice;

And the CustomException class is the following:

@Getter
public class CustomException {

    private final String message;
    private final String errorCode;
    private final String errorType;
    private final Exception exceptionDetail;
    
    public CustomException(String message, String errorCode, String errorType, Exception exceptionDetail) {
        this.message = message;
        this.errorCode = errorCode;
        this.errorType = errorType;
        this.exceptionDetail = exceptionDetail;
    }

When the response is 200, the response is like:

{
  "product": {
    "id": "12345",
    "productName": "Product name",
    "productDescription": "This is a description",
    "unitPrice": 3.25
  },
  "customException": null
}

But when the response is 500, the response is like:

{
  "product": "null,",
  "customException": {
    "message": "/ by zero",
    "errorCode": "500",
    "errorType": "Internal server error",
    "exceptionDetail": null,
    "cause": null,
    "stackTrace": [
      {
        "classLoaderName": "app",
        "moduleName": null,
        "moduleVersion": null,
        "methodName": "getProductById",
        "fileName": "TestControllerImpl.java",
        "lineNumber": 33,
        "className": "com.myproject.testmicroservice.controller.impl.TestControllerImpl",
        "nativeMethod": false
      }
    ]
  }
}

How can I add a custom example in the @ApiResponse annotation?