private static boolean eq(Object o1, Object o2) {
            return o1 == null ? o2 == null : o1.equals(o2);
        }
Returns an enumeration of the values in this table.

@return an enumeration of the values in this table
@see #values()
commons-profiler/src/main/java/com/navercorp/pinpoint/common/profiler/concurrent/jsr166/ConcurrentReferenceHashMap.java