Separate factory method cache for introspection purposes

Issue: SPR-17358
Issue: SPR-8891

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java

@@ -775,6 +775,7 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 			}
 		}
 
+		mbd.factoryMethodToIntrospect = uniqueCandidate;
 		if (commonType == null) {
 			return null;
 		}

spring-beans/src/main/java/org/springframework/beans/factory/support/ConstructorResolver.java

@@ -337,9 +337,7 @@ class ConstructorResolver {
 				}
 			}
 		}
-		synchronized (mbd.constructorArgumentLock) {
-			mbd.resolvedConstructorOrFactoryMethod = uniqueCandidate;
-		}
+		mbd.factoryMethodToIntrospect = uniqueCandidate;
 	}
 
 	/**
@@ -448,6 +446,7 @@ class ConstructorResolver {
 			if (candidateList.size() == 1 && explicitArgs == null && !mbd.hasConstructorArgumentValues()) {
 				Method uniqueCandidate = candidateList.get(0);
 				if (uniqueCandidate.getParameterCount() == 0) {
+					mbd.factoryMethodToIntrospect = uniqueCandidate;
 					synchronized (mbd.constructorArgumentLock) {
 						mbd.resolvedConstructorOrFactoryMethod = uniqueCandidate;
 						mbd.constructorArgumentsResolved = true;
@@ -598,6 +597,7 @@ class ConstructorResolver {
 			}
 
 			if (explicitArgs == null && argsHolderToUse != null) {
+				mbd.factoryMethodToIntrospect = factoryMethodToUse;
 				argsHolderToUse.storeCache(mbd, factoryMethodToUse);
 			}
 		}

spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultListableBeanFactory.java

@@ -755,14 +755,8 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 
 		String beanDefinitionName = BeanFactoryUtils.transformedBeanName(beanName);
 		resolveBeanClass(mbd, beanDefinitionName);
-		if (mbd.isFactoryMethodUnique) {
-			boolean resolve;
-			synchronized (mbd.constructorArgumentLock) {
-				resolve = (mbd.resolvedConstructorOrFactoryMethod == null);
-			}
-			if (resolve) {
-				new ConstructorResolver(this).resolveFactoryMethodIfPossible(mbd);
-			}
+		if (mbd.isFactoryMethodUnique && mbd.factoryMethodToIntrospect == null) {
+			new ConstructorResolver(this).resolveFactoryMethodIfPossible(mbd);
 		}
 		return resolver.isAutowireCandidate(
 				new BeanDefinitionHolder(mbd, beanName, getAliases(beanDefinitionName)), descriptor);

spring-beans/src/main/java/org/springframework/beans/factory/support/RootBeanDefinition.java

@@ -75,6 +75,10 @@ public class RootBeanDefinition extends AbstractBeanDefinition {
 	@Nullable
 	volatile ResolvableType factoryMethodReturnType;
 
+	/** Package-visible field for caching a unique factory method candidate for introspection. */
+	@Nullable
+	volatile Method factoryMethodToIntrospect;
+
 	/** Common lock for the four constructor fields below. */
 	final Object constructorArgumentLock = new Object();
 
@@ -370,10 +374,7 @@ public class RootBeanDefinition extends AbstractBeanDefinition {
 	 */
 	@Nullable
 	public Method getResolvedFactoryMethod() {
-		synchronized (this.constructorArgumentLock) {
-			Executable candidate = this.resolvedConstructorOrFactoryMethod;
-			return (candidate instanceof Method ? (Method) candidate : null);
-		}
+		return this.factoryMethodToIntrospect;
 	}
 
 	public void registerExternallyManagedConfigMember(Member configMember) {

spring-context/src/test/java/org/springframework/context/annotation/configuration/BeanMethodQualificationTests.java

@@ -83,8 +83,8 @@ public class BeanMethodQualificationTests {
 				new AnnotationConfigApplicationContext(CustomConfig.class, CustomPojo.class);
 		assertFalse(ctx.getBeanFactory().containsSingleton("testBean1"));
 		assertFalse(ctx.getBeanFactory().containsSingleton("testBean2"));
-		// TODO: assertTrue(BeanFactoryAnnotationUtils.isQualifierMatch(value -> value.equals("boring"),
-		//		"testBean2", ctx.getDefaultListableBeanFactory()));
+		assertTrue(BeanFactoryAnnotationUtils.isQualifierMatch(value -> value.equals("boring"),
+				"testBean2", ctx.getDefaultListableBeanFactory()));
 		CustomPojo pojo = ctx.getBean(CustomPojo.class);
 		assertThat(pojo.testBean.getName(), equalTo("interesting"));
 		TestBean testBean2 = BeanFactoryAnnotationUtils.qualifiedBeanOfType(