LambdaMetaFactory and method handle implementation both dynamically spin classes and defined as hidden classes. It has its own implementation to dump generated code for debugging. A shared utility to dump generated code defined via Lookup::defineClass, Lookup::defineHiddenClass and Lookup::defineHiddenClassWithClassData would be useful.

To dump lambda proxy classes, set this system property:
   -Djdk.internal.lambda.dumpProxyClasses=<dir>

To dump LambdaForms for method handle implementation, set this system property:
   -Djava.lang.invoke.MethodHandle.DUMP_CLASS_FILES=true

This can add a system property to dump classes defined via Lookup API for other generated classes.