The VM has access to inner class info as stored in the InnerClass classfile attribute. The JVMDI should provide access to this information so that a debugger back end does not have to resort to scanning class names.

Something like JVMDI_GetMemberClasses(JNIEnv *, jclass, int count, jclass **) and JVMDI_GetEnclosingClass(JNIEnv *, jclass, jclass **) would do the trick.