Avoid passing null as argument marked as non-nullable

Closes gh-35933
Signed-off-by: jnizet <jb@ninja-squad.com>

Author: jnizet

spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/integration/MockitoSpyBeanWithGenericsOnTestFieldForExistingGenericBeanProducedByFactoryBeanIntegrationTests.java

@@ -75,7 +75,7 @@ public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata,
 
 			RootBeanDefinition definition = new RootBeanDefinition(ExampleGenericServiceFactoryBean.class);
 			ResolvableType targetType = ResolvableType.forClassWithGenerics(
-					ExampleGenericServiceFactoryBean.class, null, ExampleGenericService.class);
+					ExampleGenericServiceFactoryBean.class, Object.class, ExampleGenericService.class);
 			definition.setTargetType(targetType);
 			registry.registerBeanDefinition("exampleService", definition);
 		}