Use resource loader's class loader in config loading

Previously, classes involved in config loading used a variety of
potentially different class loaders when calling SpringFactoriesLoader.
Some classes would use their own class loader and others would use null
which results in SpringFactoriesLoader's class loader being used.

This commit updates the config loading classes to consistently use the
resource loader's class loader.

Fixes gh-26126

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataEnvironment.java

@@ -152,7 +152,7 @@ class ConfigDataEnvironment {
 		this.additionalProfiles = additionalProfiles;
 		this.environmentUpdateListener = (environmentUpdateListener != null) ? environmentUpdateListener
 				: ConfigDataEnvironmentUpdateListener.NONE;
-		this.loaders = new ConfigDataLoaders(logFactory, bootstrapContext);
+		this.loaders = new ConfigDataLoaders(logFactory, bootstrapContext, resourceLoader.getClassLoader());
 		this.contributors = createContributors(binder);
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataLoaders.java

@@ -51,9 +51,11 @@ class ConfigDataLoaders {
 	 * Create a new {@link ConfigDataLoaders} instance.
 	 * @param logFactory the deferred log factory
 	 * @param bootstrapContext the bootstrap context
+	 * @param classLoader the class loader used when loading from {@code spring.factories}
 	 */
-	ConfigDataLoaders(DeferredLogFactory logFactory, ConfigurableBootstrapContext bootstrapContext) {
-		this(logFactory, bootstrapContext, SpringFactoriesLoader.loadFactoryNames(ConfigDataLoader.class, null));
+	ConfigDataLoaders(DeferredLogFactory logFactory, ConfigurableBootstrapContext bootstrapContext,
+			ClassLoader classLoader) {
+		this(logFactory, bootstrapContext, SpringFactoriesLoader.loadFactoryNames(ConfigDataLoader.class, classLoader));
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataLocationResolvers.java

@@ -54,7 +54,7 @@ class ConfigDataLocationResolvers {
 	ConfigDataLocationResolvers(DeferredLogFactory logFactory, ConfigurableBootstrapContext bootstrapContext,
 			Binder binder, ResourceLoader resourceLoader) {
 		this(logFactory, bootstrapContext, binder, resourceLoader, SpringFactoriesLoader
-				.loadFactoryNames(ConfigDataLocationResolver.class, ConfigDataLocationResolver.class.getClassLoader()));
+				.loadFactoryNames(ConfigDataLocationResolver.class, resourceLoader.getClassLoader()));
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigFileApplicationListener.java

@@ -316,7 +316,7 @@ private class Loader {
 			this.placeholdersResolver = new PropertySourcesPlaceholdersResolver(this.environment);
 			this.resourceLoader = (resourceLoader != null) ? resourceLoader : new DefaultResourceLoader(null);
 			this.propertySourceLoaders = SpringFactoriesLoader.loadFactories(PropertySourceLoader.class,
-					getClass().getClassLoader());
+					this.resourceLoader.getClassLoader());
 		}
 
 		void load() {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentContributorsTests.java

@@ -37,6 +37,7 @@
 import org.springframework.boot.context.properties.bind.BindException;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.boot.logging.DeferredLogFactory;
+import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.mock.env.MockEnvironment;
 import org.springframework.mock.env.MockPropertySource;
 
@@ -84,8 +85,9 @@ void setup() {
 		this.environment = new MockEnvironment();
 		this.binder = Binder.get(this.environment);
 		ConfigDataLocationResolvers resolvers = new ConfigDataLocationResolvers(this.logFactory, this.bootstrapContext,
-				this.binder, null);
-		ConfigDataLoaders loaders = new ConfigDataLoaders(this.logFactory, this.bootstrapContext);
+				this.binder, new DefaultResourceLoader(getClass().getClassLoader()));
+		ConfigDataLoaders loaders = new ConfigDataLoaders(this.logFactory, this.bootstrapContext,
+				getClass().getClassLoader());
 		this.importer = new ConfigDataImporter(this.logFactory, ConfigDataNotFoundAction.FAIL, resolvers, loaders);
 		this.activationContext = new ConfigDataActivationContext(CloudPlatform.KUBERNETES, null);
 	}