Cache AbstractBeanFactory.isFactoryBean results

Add an additional cache to the `RootBeanDefinition` to save
recalculating the result of `isFactoryBean`.

Closes gh-23337

Author: philwebb

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

@@ -1333,6 +1333,7 @@ private void copyRelevantMergedBeanDefinitionCaches(RootBeanDefinition previous,
 				ObjectUtils.nullSafeEquals(mbd.getFactoryMethodName(), previous.getFactoryMethodName()) &&
 				(mbd.targetType == null || mbd.targetType.equals(previous.targetType))) {
 			mbd.targetType = previous.targetType;
+			mbd.isFactoryBean = previous.isFactoryBean;
 			mbd.resolvedTargetType = previous.resolvedTargetType;
 			mbd.factoryMethodReturnType = previous.factoryMethodReturnType;
 			mbd.factoryMethodToIntrospect = previous.factoryMethodToIntrospect;
@@ -1541,8 +1542,13 @@ protected Class<?> predictBeanType(String beanName, RootBeanDefinition mbd, Clas
 	 * @param mbd the corresponding bean definition
 	 */
 	protected boolean isFactoryBean(String beanName, RootBeanDefinition mbd) {
-		Class<?> beanType = predictBeanType(beanName, mbd, FactoryBean.class);
-		return (beanType != null && FactoryBean.class.isAssignableFrom(beanType));
+		Boolean result = mbd.isFactoryBean;
+		if (result == null) {
+			Class<?> beanType = predictBeanType(beanName, mbd, FactoryBean.class);
+			result = beanType != null && FactoryBean.class.isAssignableFrom(beanType);
+			mbd.isFactoryBean = result;
+		}
+		return result;
 	}
 
 	/**

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

@@ -74,6 +74,10 @@ public class RootBeanDefinition extends AbstractBeanDefinition {
 	@Nullable
 	volatile Class<?> resolvedTargetType;
 
+	/** Package-visible field for caching if the bean is a factory bean. */
+	@Nullable
+	volatile Boolean isFactoryBean;
+
 	/** Package-visible field for caching the return type of a generically typed factory method. */
 	@Nullable
 	volatile ResolvableType factoryMethodReturnType;