core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/Transformer.java

@@ -60,11 +60,11 @@
         @Override
         public byte[] transform(
                 ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain,
                 byte[] classfileBuffer) throws IllegalClassFormatException {
                 if (!registry.hasPendingTransforms(className)) {
-                        return classfileBuffer;
+                        return null;
                 }
                 return doTransforms(registry.getTransformData(className), classfileBuffer, loader, protectionDomain);
         }
 
         private byte[] doTransforms(