Resolver error occurs when use custom OpenApiCustomiser to GroupedOpenApi

[doljae]

Describe the bug

• Resolver error occurs when use custom OpenApiCustomiser to GroupedOpenApi
• without addOpenApiCustomiser(), it works well.

To Reproduce
Steps to reproduce the behavior:

• What version of spring-boot you are using?, 2.6.3
• What modules and versions of springdoc-openapi are you using?, latest
• Provide with a sample code (HelloController) or Test that reproduces the problem

@Configuration
public class SwaggerOpenApiConfiguration {

    @Bean
    public GroupedOpenApi channelApiGroup() {
        // sample conditions for GroupedOpenApi
        String[] paths = { "/v1/pet/**" };
        return GroupedOpenApi.builder().group("channel-gateway")
                             .pathToMatch(paths)
                             // if comment out the line below, resolver error occurs
                             .addOpenApiCustomiser(globalOpenApiCustomer())
                             .build();
    }

    public static OpenApiCustomiser globalOpenApiCustomer() {
        return openApi ->
            openApi.info(new Info()
                             .title(TITLE)
                             .description(DESCRIPTION)
                             .license(new License().name(LICENSE).url(LICENSE_URL))
                             .termsOfService(TERMS_OF_SERVICE_URL)
                             .version(VERSION))
                    // plus the request header also invisible
                   .components(new Components()
                                   .addParameters("test",
                                                  new Parameter()
                                                      .name("testHeader")
                                                      .required(true)
                                                      .in("header")
                                                      .description("testDescription").
                                                      schema(new StringSchema())))
    }
}

Expected behavior

• The swagger-ui.html work without any errors like demo springdoc-openapi swagger-ui.html page

Screenshots

Additional context

• Plus, I add custom headers for trying out swagger with parameters, it is invisible.

[doljae]

First of all, I found out that I was using it incorrectly.

I created an empty project, made an MVC structure simple, and tested it by adding options one by one.

The first problem was the StringSchema() declared within the components() of the globalOpenApiCustomer() I wrote. When I erased the components() part, the error disappeared.

And referring to this code, I succeeded in adding a header.

The code is as follows.

Code 1

@Configuration
public class SwaggerConfig {

    private static final String TITLE = "TITLE";
    private static final String DESCRIPTION = "DESCRIPTION";
    private static final String LICENSE = "LICENSE";
    private static final String LICENSE_URL = "LICENSE_URL";
    private static final String TERMS_OF_SERVICE_URL = "TERMS_OF_SERVICE_URL";
    private static final String VERSION = "VERSION";

    @Bean
    public GroupedOpenApi catApiGroup() {
        return GroupedOpenApi.builder()
                             .group("cat-group")
                             .pathsToMatch("/cat/**")
                             .addOpenApiCustomiser(globalOpenApiCustomer())
                             .addOperationCustomizer((operation, handlerMethod) ->
                                                         operation.addParametersItem(new HeaderParameter().$ref(
                                                                      "#/components/parameters/myGlobalHeader1"))
                                                                  .addParametersItem(new HeaderParameter().$ref(
                                                                      "#/components/parameters/myGlobalHeader2"))
                                                                  .addParametersItem(new HeaderParameter().$ref(
                                                                      "#/components/parameters/myGlobalHeader3"))
                                                                  .addParametersItem(new HeaderParameter().$ref(
                                                                      "#/components/parameters/myGlobalHeader4")))
                             .build();
    }

    @Bean
    public GroupedOpenApi dogApiGroup() {
        return GroupedOpenApi.builder()
                             .group("dog-group")
                             .pathsToMatch("/dog/**")
                             .addOpenApiCustomiser(globalOpenApiCustomer())
                             .build();
    }

    public static OpenApiCustomiser globalOpenApiCustomer() {
        return openApi ->
            openApi.info(new Info()
                             .title(TITLE)
                             .description(DESCRIPTION)
                             .license(new License().name(LICENSE).url(LICENSE_URL))
                             .termsOfService(TERMS_OF_SERVICE_URL)
                             .version(VERSION));
    }

    @Bean
    public OpenAPI customOpenAPI() {
        StringSchema schema1 = new StringSchema()._default("default1");
        StringSchema schema2 = new StringSchema()._default("default2");
        StringSchema schema3 = new StringSchema()._default("default3");
        StringSchema schema4 = new StringSchema()._default("default4");
        return new OpenAPI()
            .components(new Components()
                            .addParameters("myGlobalHeader1",
                                           new HeaderParameter()
                                               .required(true)
                                               .name("My-Global-Header1")
                                               .description("My Global Header1")
                                               .schema(schema1))
                            .addParameters("myGlobalHeader2",
                                           new HeaderParameter()
                                               .required(true)
                                               .name("My-Global-Header2")
                                               .description("My Global Header2")
                                               .schema(schema2))
                            .addParameters("myGlobalHeader3",
                                           new HeaderParameter()
                                               .required(true)
                                               .name("My-Global-Header3")
                                               .description("My Global Header3")
                                               .schema(schema3))
                            .addParameters("myGlobalHeader4",
                                           new HeaderParameter()
                                               .required(true)
                                               .name("My-Global-Header4")
                                               .description("My Global Header4")
                                               .schema(schema4)));
    }
}

When this was set, it was confirmed that the header value set only for catApi was applied.

Cat API

Dog API

However, this code causes the same error mentioned in issue.

Code 2

@Configuration
public class SwaggerConfig {

    private static final String TITLE = "TITLE";
    private static final String DESCRIPTION = "DESCRIPTION";
    private static final String LICENSE = "LICENSE";
    private static final String LICENSE_URL = "LICENSE_URL";
    private static final String TERMS_OF_SERVICE_URL = "TERMS_OF_SERVICE_URL";
    private static final String VERSION = "VERSION";

    @Bean
    public GroupedOpenApi catApiGroup() {
        return GroupedOpenApi.builder()
                             .group("cat-group")
                             .pathsToMatch("/cat/**")
                             .addOpenApiCustomiser(globalOpenApiCustomer())
                             .build();
    }

    @Bean
    public GroupedOpenApi dogApiGroup() {
        return GroupedOpenApi.builder()
                             .group("dog-group")
                             .pathsToMatch("/dog/**")
                             .addOpenApiCustomiser(globalOpenApiCustomer())
                             .build();
    }

    @Bean
    public static OpenApiCustomiser globalOpenApiCustomer() {
        return openApi ->
            openApi.info(new Info()
                             .title(TITLE)
                             .description(DESCRIPTION)
                             .license(new License().name(LICENSE).url(LICENSE_URL))
                             .termsOfService(TERMS_OF_SERVICE_URL)
                             .version(VERSION))
                   .components(new Components()
                                   .addParameters("myGlobalHeader1",
                                                  new HeaderParameter()
                                                      .required(true)
                                                      .name("My-Global-Header1")
                                                      .description("My Global Header1")
                                                      .schema(new StringSchema()._default("default1")))
                                   .addParameters("myGlobalHeader2",
                                                  new HeaderParameter()
                                                      .required(true)
                                                      .name("My-Global-Header2")
                                                      .description("My Global Header2")
                                                      .schema(new StringSchema()._default("default2")))
                                   .addParameters("myGlobalHeader3",
                                                  new HeaderParameter()
                                                      .required(true)
                                                      .name("My-Global-Header3")
                                                      .description("My Global Header3")
                                                      .schema(new StringSchema()._default("default3")))
                                   .addParameters("myGlobalHeader4",
                                                  new HeaderParameter()
                                                      .required(true)
                                                      .name("My-Global-Header4")
                                                      .description("My Global Header4")
                                                      .schema(new StringSchema()._default("default4"))));

    }
}

There are two things I want to ask...

1. Even in the normally operated code, the four custom header values set should also be seen in dog-api, but were not seen in swagger-ui. Does OpenApi Bean set up globally except for groups?
2. Please explain the cause of this error & difference between Code 1 & Code 2

Plus, I think there's a better way to add a custom header(for globally or specific group or etc).
Thank you for letting me know the reference link or sample code for the purpose I mentioned.

[bnasslahsen]

@doljae,

It's already explained here.