SpringBoot Custom ConfigDataLocationResolver/ConfigDataLoader fails in 3.0.x when combined with spring-boot-devtools

Using ConfigDataLocationResolver/ConfigDataLoader in 3.0.2 in combination with spring-boot-devtools leads to the following error on application start:

> Task :bootRun
09:11:43.399 [restartedMain] ERROR org.springframework.boot.SpringApplication - Application run failed
java.lang.IllegalStateException: No loader found for resource 'com.example.demo.DemoDataResource@30afc98d'
        at org.springframework.util.Assert.state(Assert.java:97)
        at org.springframework.boot.context.config.ConfigDataLoaders.getLoader(ConfigDataLoaders.java:115)
        at org.springframework.boot.context.config.ConfigDataLoaders.load(ConfigDataLoaders.java:94)
        at org.springframework.boot.context.config.ConfigDataImporter.load(ConfigDataImporter.java:128)
        at org.springframework.boot.context.config.ConfigDataImporter.resolveAndLoad(ConfigDataImporter.java:86)
        at org.springframework.boot.context.config.ConfigDataEnvironmentContributors.withProcessedImports(ConfigDataEnvironmentContributors.java:115)
        at org.springframework.boot.context.config.ConfigDataEnvironment.processInitial(ConfigDataEnvironment.java:242)
        at org.springframework.boot.context.config.ConfigDataEnvironment.processAndApply(ConfigDataEnvironment.java:229)
        at org.springframework.boot.context.config.ConfigDataEnvironmentPostProcessor.postProcessEnvironment(ConfigDataEnvironmentPostProcessor.java:96)
        at org.springframework.boot.context.config.ConfigDataEnvironmentPostProcessor.postProcessEnvironment(ConfigDataEnvironmentPostProcessor.java:89)
        at org.springframework.boot.env.EnvironmentPostProcessorApplicationListener.onApplicationEnvironmentPreparedEvent(EnvironmentPostProcessorApplicationListener.java:109)
        at org.springframework.boot.env.EnvironmentPostProcessorApplicationListener.onApplicationEvent(EnvironmentPostProcessorApplicationListener.java:94)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:131)
        at org.springframework.boot.context.event.EventPublishingRunListener.multicastInitialEvent(EventPublishingRunListener.java:136)
        at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:81)
        at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$2(SpringApplicationRunListeners.java:64)
        at java.base/java.lang.Iterable.forEach(Iterable.java:75)
        at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:118)
        at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:112)
        at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:63)
        at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:354)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:305)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1304)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1293)
        at com.example.demo.DemoApplication.main(DemoApplication.java:10)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:568)
        at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)

I've create sample applications for spring boot 2.7.8 and 3.0.2. Spring boot 2.7.8 works, 3.0.2 fails to start. Please run the command gradlew clean bootRun in each directory. Here is the link to my sample git repository: https://github.com/sestrel/ConfigDataLocationResolver

The comparison in line https://github.com/spring-projects/spring-boot/blob/main/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataLoaders.java#L104 seems to fail because type and instance have different ClassLoaders in 3.0.2.

Comment From: sbrannen

I've edited your comment to improve the formatting. You might want to check out this Mastering Markdown guide for future reference.

Comment From: wilkinsona

This is a regression introduced in https://github.com/spring-projects/spring-boot/commit/770cb840c32869cf8f8935d6acd8e7b8e88093c8. We're no longer passing in the resource loader's class loader when loading the config data loaders.