Attempt to fix failing CI builds

Author: sbrannen

spring-test/src/main/java/org/springframework/test/context/TestContextAnnotationUtils.java

@@ -75,7 +75,7 @@ public abstract class TestContextAnnotationUtils {
 	private static final ConcurrentLruCache<Class<?>, EnclosingConfiguration> cachedEnclosingConfigurationModes =
 			new ConcurrentLruCache<>(32, TestContextAnnotationUtils::lookUpEnclosingConfiguration);
 
-	private static EnclosingConfiguration defaultEnclosingConfigurationMode;
+	private static volatile EnclosingConfiguration defaultEnclosingConfigurationMode;
 
 	/**
 	 * Find the first annotation of the specified {@code annotationType} within

spring-test/src/test/java/org/springframework/test/context/TestContextAnnotationUtilsTests.java

@@ -57,6 +57,7 @@ class TestContextAnnotationUtilsTests {
 	class SearchEnclosingClassTests {
 
 		@BeforeEach
+		@AfterEach
 		void clearCaches() {
 			TestContextAnnotationUtils.clearCaches();
 		}