Modify MBeanTestUtils to work on JDK 17+

Author: sbrannen

spring-context/src/test/java/org/springframework/util/MBeanTestUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,21 +18,26 @@
 
 import java.lang.management.ManagementFactory;
 import java.lang.reflect.Field;
+import java.util.EnumSet;
 
 import javax.management.MBeanServer;
 import javax.management.MBeanServerFactory;
 
+import org.junit.jupiter.api.condition.JRE;
+
 /**
  * Utilities for MBean tests.
  *
  * @author Phillip Webb
+ * @author Sam Brannen
  */
 public class MBeanTestUtils {
 
 	/**
-	 * Resets MBeanServerFactory and ManagementFactory to a known consistent state.
-	 * <p>This involves releasing all currently registered MBeanServers and resetting
-	 * the platformMBeanServer to null.
+	 * Resets {@link MBeanServerFactory} to a known consistent state. This involves
+	 * releasing all currently registered MBeanServers.
+	 * <p>On JDK 8 - JDK 16, this method also resets the platformMBeanServer field
+	 * in {@link ManagementFactory} to {@code null}.
 	 */
 	public static synchronized void resetMBeanServers() throws Exception {
 		for (MBeanServer server : MBeanServerFactory.findMBeanServer(null)) {
@@ -46,9 +51,15 @@ public static synchronized void resetMBeanServers() throws Exception {
 			}
 		}
 
-		Field field = ManagementFactory.class.getDeclaredField("platformMBeanServer");
-		field.setAccessible(true);
-		field.set(null, null);
+		if (!isCurrentJreWithinRange(JRE.JAVA_16, JRE.OTHER)) {
+			Field field = ManagementFactory.class.getDeclaredField("platformMBeanServer");
+			field.setAccessible(true);
+			field.set(null, null);
+		}
+	}
+
+	static boolean isCurrentJreWithinRange(JRE min, JRE max) {
+		return EnumSet.range(min, max).contains(JRE.currentVersion());
 	}
 
 }

src/checkstyle/checkstyle-suppressions.xml

@@ -4,7 +4,7 @@
 
 	<!-- global -->
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/]java[\\/]" checks="AnnotationLocation|AnnotationUseStyle|AtclauseOrder|AvoidNestedBlocks|FinalClass|HideUtilityClassConstructor|InnerTypeLast|JavadocStyle|JavadocType|JavadocVariable|LeftCurly|MultipleVariableDeclarations|NeedBraces|OneTopLevelClass|OuterTypeFilename|RequireThis|SpringCatch|SpringJavadoc|SpringNoThis"/>
-	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/]java[\\/]org[\\/]springframework[\\/].+(Tests|Suite)" checks="IllegalImport" id="bannedJUnitJupiterImports"/>
+	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/]java[\\/]org[\\/]springframework[\\/].+(Tests|Suite|TestUtils)" checks="IllegalImport" id="bannedJUnitJupiterImports"/>
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/]java[\\/]" checks="SpringJUnit5" message="should not be public"/>
 	<!-- generated sources -->
 	<suppress files="[\\/]build[\\/]generated[\\/]sources[\\/]" checks=".*"/>