The following code compiles fine:

public primitive class X implements Cloneable {
    public static void main(String [] args) {
    }
}

but when run fails with:
Error: LinkageError occurred while loading main class X
java.lang.ClassFormatError: class: X - Inline Types do not support Cloneable


JEP 401 states:

(Possibly) The class does not implement Cloneable or declare a clone() method.

Javac implements the latter clause but not the former.