Allow configuring custom GraphQL argument resolvers

This commit gathers `HandlerMethodArgumentResolver` beans contributed by
the application and sets them up on the auto-configured
`AnnotatedControllerConfigurer` bean.

This allows easier registrationsfor custom argument resolvers in Spring
for GraphQL applications.

Closes gh-40393

Author: maxhov

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/graphql/GraphQlAutoConfiguration.java

@@ -49,6 +49,7 @@
 import org.springframework.core.log.LogMessage;
 import org.springframework.data.domain.ScrollPosition;
 import org.springframework.graphql.ExecutionGraphQlService;
+import org.springframework.graphql.data.method.HandlerMethodArgumentResolver;
 import org.springframework.graphql.data.method.annotation.support.AnnotatedControllerConfigurer;
 import org.springframework.graphql.data.pagination.ConnectionFieldTypeVisitor;
 import org.springframework.graphql.data.pagination.CursorEncoder;
@@ -154,11 +155,13 @@ public ExecutionGraphQlService executionGraphQlService(GraphQlSource graphQlSour
 	@Bean
 	@ConditionalOnMissingBean
 	public AnnotatedControllerConfigurer annotatedControllerConfigurer(
-			@Qualifier(TaskExecutionAutoConfiguration.APPLICATION_TASK_EXECUTOR_BEAN_NAME) ObjectProvider<Executor> executorProvider) {
+			@Qualifier(TaskExecutionAutoConfiguration.APPLICATION_TASK_EXECUTOR_BEAN_NAME) ObjectProvider<Executor> executorProvider,
+			ObjectProvider<HandlerMethodArgumentResolver> argumentResolvers) {
 		AnnotatedControllerConfigurer controllerConfigurer = new AnnotatedControllerConfigurer();
 		controllerConfigurer
 			.addFormatterRegistrar((registry) -> ApplicationConversionService.addBeans(registry, this.beanFactory));
 		executorProvider.ifAvailable(controllerConfigurer::setExecutor);
+		argumentResolvers.orderedStream().forEach(controllerConfigurer::addCustomArgumentResolver);
 		return controllerConfigurer;
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/graphql/GraphQlAutoConfigurationTests.java

@@ -45,6 +45,7 @@
 import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.graphql.ExecutionGraphQlService;
+import org.springframework.graphql.data.method.HandlerMethodArgumentResolver;
 import org.springframework.graphql.data.method.annotation.support.AnnotatedControllerConfigurer;
 import org.springframework.graphql.data.pagination.EncodingCursorStrategy;
 import org.springframework.graphql.execution.BatchLoaderRegistry;
@@ -241,6 +242,15 @@ void whenCustomExecutorIsDefinedThenAnnotatedControllerConfigurerDoesNotUseIt()
 		});
 	}
 
+	@Test
+	void whenAHandlerMethodArgumentResolverIsDefinedThenAnnotatedControllerConfigurerShouldUseIt() {
+		this.contextRunner.withUserConfiguration(CustomHandlerMethodArgumentResolverConfiguration.class)
+			.run((context) -> assertThat(context.getBean(AnnotatedControllerConfigurer.class))
+				.extracting("customArgumentResolvers")
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
+				.hasSize(1));
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomGraphQlBuilderConfiguration {
 
@@ -336,4 +346,13 @@ Executor customExecutor() {
 
 	}
 
+	static class CustomHandlerMethodArgumentResolverConfiguration {
+
+		@Bean
+		HandlerMethodArgumentResolver customHandlerMethodArgumentResolver() {
+			return mock(HandlerMethodArgumentResolver.class);
+		}
+
+	}
+
 }