graphql-kotlin-spring-server-webflux-error-reproduction

Created to reproduce the error reported in ExpediaGroup/graphql-kotlin#2047 when using the com.expediagroup:graphql-kotlin-spring-server:8.1.0 library with Spring WebMvc.

Reproduction steps

1. Setup repo in IntelliJ IDEA with Java 21
2. Run ./gradlew bootRun
3. See the exception:

Error creating bean with name 'org.springframework.web.reactive.config.DelegatingWebFluxConfiguration': The Java/XML config for Spring MVC and Spring WebFlux cannot both be enabled, e.g. via @EnableWebMvc and @EnableWebFlux, in the same application.

4. If you want to see the exception with spring.main.allow-bean-definition-overriding=false in the application.yml, change that and run ./gradlew bootRun again. See the exception:

Description:

The bean 'requestMappingHandlerMapping', defined in class path resource [org/springframework/web/reactive/config/DelegatingWebFluxConfiguration.class], could not be registered. A bean with that name has already been defined in class path resource [org/springframework/web/servlet/config/annotation/DelegatingWebMvcConfiguration.class] and overriding is disabled.

Action:

Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

5. If you revert the com.expediagroup:graphql-kotlin-spring-server:8.1.0 library in the build.gradle.kts file to com.expediagroup:graphql-kotlin-spring-server:8.0.0, the application will run without exceptions.

Started ExampleApplicationKt in 1.634 seconds

6. To test the working application, go to http://localhost:8080/playground and run the following query against the http://localhost:8080/graphql server:

query() {
  exampleGet
}