Some HotSpot APIs use Klass*, even though it's clear that only InstanceKlass* can be used. Examples:

Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);

Array<Klass*>* InstanceKlass::local_interfaces();

This has led to unnecessary type casting in the code. We should replace the Klass* with InstanceKlass*.