Suppress @Nullable usage warnings in GraphQL tests

See gh-45494

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -48,6 +48,7 @@ public final class GraphQlTestDataFetchers {
 		return (environment) -> getBooksOnSale(environment.getArgument("minPages"));
 	}
 
+	@SuppressWarnings("deprecation")
 	@Nullable
 	public static Book getBookById(String id) {
 		return books.stream().filter((book) -> book.getId().equals(id)).findFirst().orElse(null);

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

@@ -169,6 +169,7 @@ class GraphQlWebFluxSecurityAutoConfigurationTests {
 
 		@PreAuthorize("hasRole('USER')")
 		@Nullable
+		@SuppressWarnings("deprecation")
 		Mono<Book> getBookdById(String id) {
 			return Mono.justOrEmpty(GraphQlTestDataFetchers.getBookById(id));
 		}

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

@@ -158,6 +158,7 @@ class GraphQlWebMvcSecurityAutoConfigurationTests {
 
 		@PreAuthorize("hasRole('USER')")
 		@Nullable
+		@SuppressWarnings("deprecation")
 		Book getBookdById(String id) {
 			return GraphQlTestDataFetchers.getBookById(id);
 		}