JVM installs loader constraints for unloaded signature classes when method resolution occurs. MethodHandle resolution took a different route and eagerly resolves signature classes instead (see sun.invoke.util.VerifyAccess::isTypeVisible). There's a micro-optimization which bypasses that logic for java.* classes. The downside is that java.* classes can show up as unloaded signature classes. It manifests as inlining failures during JIT-compilation and may cause severe performance issues.