Javac issues a raw types warning in KeyValueReference.java:

    [javac] /home/hannes/work/nashorn9-dev/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/WeakValueCache.java:55: warning: [rawtypes] found raw type: KeyValueReference
    [javac] final KeyValueReference ref = (KeyValueReference) refQueue.poll();
    [javac] ^
    [javac] missing type arguments for generic class KeyValueReference<K,V>
    [javac] where K,V are type-variables:
    [javac] K extends Object declared in class KeyValueReference
    [javac] V extends Object declared in class KeyValueReference