Recreate proxied @ConfigurationProperties beans on rebind

[seonghyeoklee]

Summary

When a @ConfigurationProperties bean is wrapped in an AOP proxy and properties are removed from the Environment, calling rebind() previously left field initializers unrestored (they became null / 0 / false instead of their declared default values).

This change modifies ConfigurationPropertiesRebinder.rebind() so that when the bean is an AOP proxy, a fresh instance is created via createBean() and the proxy's TargetSource is replaced, ensuring field initializers are properly restored.

Non-proxied beans continue to use the existing destroyBean() + initializeBean() behavior for backwards compatibility.

Fixes gh-1616

Changes

• ConfigurationPropertiesRebinder: detect proxied beans and replace the proxy target with a freshly created instance
• Added ConfigurationPropertiesRebinderFieldInitializerIntegrationTests to verify field initializer restoration

[ryanjbaxter]

Can you sign the commits so the DCO passes?

[seonghyeoklee]

Hi @ryanjbaxter, I've updated the commit with Signed-off-by and the DCO check is now passing. Could you take a look when you get a chance? Thanks!

[ryanjbaxter]

Can you merge in the latest changes from main so the build will pass?

[Copilot]

Pull request overview

This PR fixes ConfigurationPropertiesRebinder.rebind() behavior for AOP-proxied @ConfigurationProperties beans so that when properties are removed from the Environment, rebinding restores Java field initializer defaults (instead of leaving primitives/refs at JVM defaults). It does so by recreating the proxied target instance and swapping the proxy’s TargetSource, and adds an integration test to verify the regression.

Changes:

• Update ConfigurationPropertiesRebinder to detect AOP proxies and replace the proxy’s target with a newly created instance on rebind.
• Keep existing destroyBean() + initializeBean() behavior for non-proxied beans for compatibility.
• Add integration tests covering field-initializer restoration after property removal for proxied beans.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
spring-cloud-context/src/main/java/org/springframework/cloud/context/properties/ConfigurationPropertiesRebinder.java	Rebind now recreates and swaps the target instance when the bean is AOP-proxied.
spring-cloud-context/src/test/java/org/springframework/cloud/context/properties/ConfigurationPropertiesRebinderFieldInitializerIntegrationTests.java	New integration test validating field-initializer defaults are restored after property removal + rebind through a proxy.

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[Copilot]

createBean(target.getClass()) will run the full BeanPostProcessor chain, including auto-proxying. In an AOP-enabled context this can return another AOP proxy, and setting that proxy as the target of the existing proxy can lead to nested proxies (e.g., advice executing twice) and unexpected behavior. Consider unwrapping freshBean to its ultimate target (or otherwise ensuring the replacement target is not itself proxied) before wrapping it in the SingletonTargetSource.

[Copilot]

The proxy-target replacement destroys the existing target before creating/switching to the fresh instance. If createBean(...) or setTargetSource(...) throws, the proxy can be left pointing at an already-destroyed target, potentially breaking the application after a failed rebind(). Consider creating the fresh instance first and only swapping/destroying once that succeeds (or ensuring rollback on failure).

Suggested change

	appContext.getAutowireCapableBeanFactory().destroyBean(target);
	if (proxied && bean instanceof Advised advised) {
	Object freshBean = appContext.getAutowireCapableBeanFactory().createBean(target.getClass());
	advised.setTargetSource(new org.springframework.aop.target.SingletonTargetSource(freshBean));
	}
	else {
	if (proxied && bean instanceof Advised advised) {
	Object freshBean = appContext.getAutowireCapableBeanFactory().createBean(target.getClass());
	try {
	advised.setTargetSource(new org.springframework.aop.target.SingletonTargetSource(freshBean));
	}
	catch (Exception e) {
	appContext.getAutowireCapableBeanFactory().destroyBean(freshBean);
	throw e;
	}
	appContext.getAutowireCapableBeanFactory().destroyBean(target);
	}
	else {
	appContext.getAutowireCapableBeanFactory().destroyBean(target);

[seonghyeoklee]

Hi @ryanjbaxter, I've addressed the review feedback in c73c01c:

1. Nested proxy prevention: freshBean is now unwrapped via ProxyUtils.getTargetObject() if createBean() returns an AOP proxy, avoiding double-proxied targets.
2. Error safety: The fresh instance is created before destroying the old target. If setTargetSource() fails, the fresh bean is cleaned up and the original target remains intact.

Tests pass. Would appreciate a review when you get a chance. Thanks!

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[Copilot]

The new proxy branch assumes the proxy wraps a concrete target instance. If ProxyUtils.getTargetObject(bean) returns the proxy itself (e.g., proxies backed by a TargetSource that returns null, such as interface proxies created via ProxyFactory/EmptyTargetSource), then target.getClass() will be the proxy class and createBean(target.getClass()) will fail. Also, unconditionally replacing the proxy TargetSource can break non-singleton proxies (e.g., other scoped proxies). Consider restricting this path to proxies backed by a SingletonTargetSource (and/or only when target != bean and AopUtils.isAopProxy(target) is false), otherwise fall back to the existing destroy/initialize behavior.

Suggested change

	if (proxied && bean instanceof Advised advised) {
	if (proxied && bean instanceof Advised advised
	&& advised.getTargetSource() instanceof org.springframework.aop.target.SingletonTargetSource
	&& target != bean && !AopUtils.isAopProxy(target)) {