public boolean contains(Object o) {
            return ConcurrentWeakHashMap.this.containsValue(o);
        }
Set our entry's value and write through to the map. The
value to return is somewhat arbitrary here. Since a
WriteThroughEntry does not necessarily track asynchronous
changes, the most recent "previous" value could be
different from what we return (or could even have been
removed in which case the put will re-establish). We do not
and cannot guarantee more.
commons-profiler/src/main/java/com/navercorp/pinpoint/common/profiler/concurrent/jsr166/ConcurrentWeakHashMap.java