Reuse BatchLoaderRegistry in GraphQlService

See gh-29929

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

@@ -123,9 +123,9 @@ public class GraphQlAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	public GraphQlService graphQlService(GraphQlSource graphQlSource) {
+	public GraphQlService graphQlService(GraphQlSource graphQlSource, BatchLoaderRegistry batchLoaderRegistry) {
 		ExecutionGraphQlService service = new ExecutionGraphQlService(graphQlSource);
-		service.addDataLoaderRegistrar(this.batchLoaderRegistry);
+		service.addDataLoaderRegistrar(batchLoaderRegistry);
 		return service;
 	}
 

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

@@ -169,6 +169,14 @@ class GraphQlAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void shouldConfigCustomBatchLoaderRegistry() {
+		this.contextRunner.withUserConfiguration(CustomBatchLoaderRegistryConfiguration.class).run((context) -> {
+			assertThat(context).getBeanNames(BatchLoaderRegistry.class).containsOnly("customBatchLoaderRegistry");
+			assertThat(context).hasSingleBean(BatchLoaderRegistry.class);
+		});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomGraphQlBuilderConfiguration {
 
@@ -253,4 +261,14 @@ class GraphQlAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class CustomBatchLoaderRegistryConfiguration {
+
+		@Bean
+		BatchLoaderRegistry customBatchLoaderRegistry() {
+			return mock(BatchLoaderRegistry.class);
+		}
+
+	}
+
 }