Propagate getFactoryMethod() when using InstanceSupplier.andThen()

Update `InstanceSupplier.andThen` to propagate the result of
`getFactoryMethod()`.

See gh-28748

Author: philwebb

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

@@ -75,8 +75,19 @@ default Method getFactoryMethod() {
 	default <V> InstanceSupplier<V> andThen(
 			ThrowingBiFunction<RegisteredBean, ? super T, ? extends V> after) {
 		Assert.notNull(after, "After must not be null");
-		return registeredBean -> after.applyWithException(registeredBean,
-				get(registeredBean));
+		return new InstanceSupplier<V>() {
+
+			@Override
+			public V get(RegisteredBean registeredBean) throws Exception {
+				return after.applyWithException(registeredBean, InstanceSupplier.this.get(registeredBean));
+			}
+
+			@Override
+			public Method getFactoryMethod() {
+				return InstanceSupplier.this.getFactoryMethod();
+			}
+
+		};
 	}
 
 	/**
@@ -94,6 +105,35 @@ static <T> InstanceSupplier<T> using(ThrowingSupplier<T> supplier) {
 		return registeredBean -> supplier.getWithException();
 	}
 
+	/**
+	 * Factory method to create an {@link InstanceSupplier} from a
+	 * {@link ThrowingSupplier}.
+	 * @param <T> the type of instance supplied by this supplier
+	 * @param factoryMethod the factory method being used
+	 * @param supplier the source supplier
+	 * @return a new {@link InstanceSupplier}
+	 */
+	static <T> InstanceSupplier<T> using(@Nullable Method factoryMethod, ThrowingSupplier<T> supplier) {
+		Assert.notNull(supplier, "Supplier must not be null");
+		if (supplier instanceof InstanceSupplier<T> instanceSupplier
+				&& instanceSupplier.getFactoryMethod() == factoryMethod) {
+			return instanceSupplier;
+		}
+		return new InstanceSupplier<T>() {
+
+			@Override
+			public T get(RegisteredBean registeredBean) throws Exception {
+				return supplier.getWithException();
+			}
+
+			@Override
+			public Method getFactoryMethod() {
+				return factoryMethod;
+			}
+
+		};
+	}
+
 	/**
 	 * Lambda friendly method that can be used to create a
 	 * {@link InstanceSupplier} and add post processors in a single call. For

spring-beans/src/test/java/org/springframework/beans/factory/support/InstanceSupplierTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.beans.factory.support;
 
+import java.lang.reflect.Method;
+
 import org.junit.jupiter.api.Test;
 
 import org.springframework.util.function.ThrowingBiFunction;
@@ -55,21 +57,31 @@ void getReturnsResult() throws Exception {
 	}
 
 	@Test
-	void andThenWithBiFunctionWhenFunctionIsNullThrowsException() {
+	void andThenWhenFunctionIsNullThrowsException() {
 		InstanceSupplier<String> supplier = registeredBean -> "test";
 		ThrowingBiFunction<RegisteredBean, String, String> after = null;
 		assertThatIllegalArgumentException().isThrownBy(() -> supplier.andThen(after))
 				.withMessage("After must not be null");
 	}
 
 	@Test
-	void andThenWithBiFunctionAppliesFunctionToObtainResult() throws Exception {
+	void andThenAppliesFunctionToObtainResult() throws Exception {
 		InstanceSupplier<String> supplier = registeredBean -> "bean";
 		supplier = supplier.andThen(
 				(registeredBean, string) -> registeredBean.getBeanName() + "-" + string);
 		assertThat(supplier.get(this.registeredBean)).isEqualTo("test-bean");
 	}
 
+	@Test
+	void andThenWhenInstanceSupplierHasFactoryMethod() throws Exception {
+		Method factoryMethod = getClass().getDeclaredMethod("andThenWhenInstanceSupplierHasFactoryMethod");
+		InstanceSupplier<String> supplier = InstanceSupplier.using(factoryMethod, () -> "bean");
+		supplier = supplier.andThen(
+				(registeredBean, string) -> registeredBean.getBeanName() + "-" + string);
+		assertThat(supplier.get(this.registeredBean)).isEqualTo("test-bean");
+		assertThat(supplier.getFactoryMethod()).isSameAs(factoryMethod);
+	}
+
 	@Test
 	void ofSupplierWhenInstanceSupplierReturnsSameInstance() {
 		InstanceSupplier<String> supplier = registeredBean -> "test";