Start building against Spring Framework 6.1.0-M4 snapshots

See gh-36678

gradle.properties

@@ -6,7 +6,7 @@ org.gradle.jvmargs=-Xmx2g -Dfile.encoding=UTF-8
 
 kotlinVersion=1.9.0
 nativeBuildToolsVersion=0.9.23
-springFrameworkVersion=6.1.0-M3
+springFrameworkVersion=6.1.0-SNAPSHOT
 tomcatVersion=10.1.11
 
 kotlin.stdlib.default.dependency=false

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootContextLoader.java

@@ -230,8 +230,8 @@ public class SpringBootContextLoader extends AbstractContextLoader implements Ao
 		setActiveProfiles(environment, mergedConfig.getActiveProfiles(), applicationEnvironment);
 		ResourceLoader resourceLoader = (application.getResourceLoader() != null) ? application.getResourceLoader()
 				: new DefaultResourceLoader(null);
-		TestPropertySourceUtils.addPropertiesFilesToEnvironment(environment, resourceLoader,
-				mergedConfig.getPropertySourceLocations());
+		TestPropertySourceUtils.addPropertySourcesToEnvironment(environment, resourceLoader,
+				mergedConfig.getPropertySourceDescriptors());
 		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(environment, getInlinedProperties(mergedConfig));
 	}
 

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootTestContextBootstrapper.java

@@ -376,7 +376,7 @@ public class SpringBootTestContextBootstrapper extends DefaultTestContextBootstr
 		contextCustomizers.add(new SpringBootTestAnnotation(mergedConfig.getTestClass()));
 		return new MergedContextConfiguration(mergedConfig.getTestClass(), mergedConfig.getLocations(), classes,
 				mergedConfig.getContextInitializerClasses(), mergedConfig.getActiveProfiles(),
-				mergedConfig.getPropertySourceLocations(), propertySourceProperties, contextCustomizers,
+				mergedConfig.getPropertySourceDescriptors(), propertySourceProperties, contextCustomizers,
 				mergedConfig.getContextLoader(), getCacheAwareContextLoaderDelegate(), mergedConfig.getParent());
 	}