SynchronizedNavigableSet tailSet uses wrong mutex

FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
In the version of the tailSet method taking two arguments, in the implementation of java.util.Collections.SynchronizedNavigableSet, the method creates a new SynchronizedNavigableSet using the default mutex (this) rather than the correct mutex object for that set.

This is the offending code:

    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
        synchronized (mutex) {
            return new SynchronizedNavigableSet<>(ns.tailSet(fromElement, inclusive));
        }
    }

Should be:

    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
        synchronized (mutex) {
            return new SynchronizedNavigableSet<>(ns.tailSet(fromElement, inclusive), mutex);
        }
    }


REPRODUCIBILITY :
This bug can be reproduced always.