Unnecessary replication of class descriptors for common non-public JDK classes

This includes abstract JDK classes whose implementation classes are non-public.
e.g.

• java.time.Clock
• java.time.ZoneId
• java.util.Locale

including java.util.Collections wrapper classes for which no externalizers exist:
e.g.

• Collections.checked*();
• Collections.synchronized*();
• Collections.unmodifiable*();