integration tests: NullPointerExceptions contain now a description in Java 16+

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1885549 13f79535-47bb-0310-9956-ffa450edef68

src/integrationtest/org/apache/poi/stress/TestAllFiles.java

@@ -88,7 +88,15 @@ import org.opentest4j.AssertionFailedError;
 @Execution(ExecutionMode.CONCURRENT)
 public class TestAllFiles {
     private static final File ROOT_DIR = new File("test-data");
+    private static final int jreVersion;
 
+    static {
+        String version = System.getProperty("java.version");
+        String major = version.startsWith("1.")
+            ? version.substring(2, 3)
+            : version.substring(0, version.indexOf("."));
+        jreVersion = Integer.parseInt(major);
+    }
 
     public static final String[] SCAN_EXCLUDES = {
         "**/.svn/**",
@@ -204,7 +212,7 @@ public class TestAllFiles {
         } else if (exClass != null) {
             Exception e = assertThrows((Class<? extends Exception>)exClass, exec);
             String actMsg = e.getMessage();
-            if (exMessage == null) {
+            if ((NullPointerException.class.isAssignableFrom(exClass) && jreVersion < 16) || exMessage == null) {
                 assertNull(actMsg);
             } else {
                 assertNotNull(actMsg);