--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/runtime/cds/appcds/jvmti/InstrumentationClassFileTransformer.java	Mon Jul 29 10:34:20 2019 -0400
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.IllegalClassFormatException;
+import java.security.ProtectionDomain;
+
+// Note: Util is from /test/hotspot/jtreg/runtime/cds/appcds/test-classes/TestCommon.java
+
+public class InstrumentationClassFileTransformer implements ClassFileTransformer {
+    public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,
+                            ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {
+
+        if (name.startsWith("InstrumentationApp$") && !name.equals("InstrumentationApp$NotTransformed")) {
+            System.out.println("Transforming: " + name + " class = " + classBeingRedefined);
+            try {
+                if (classBeingRedefined == null) {
+                    // Initial transform
+                    replace(buffer, "buzz", "fuzz");
+                } else {
+                    replace(buffer, "buzz", "guzz"); // Retransform
+                    replace(buffer, "huzz", "quzz"); // Redefine
+                }
+            } catch (Throwable t) {
+                t.printStackTrace();
+            }
+            return buffer;
+        }
+        return null;
+    }
+
+    static void replace(byte[] buffer, String from, String to) {
+        int n = Util.replace(buffer, from, to);
+        System.out.println("..... replaced " + n + " occurrence(s) of '" + from + "' to '" + to + "'");
+    }
+}