public boolean remove     ( Object key,Object val ) {
    return objectsEquals(putIfMatch( key,TOMBSTONE, val ), val);
  }
Atomically do a {@link #remove(Object)} if-and-only-if the key is mapped
 to a value which is <code>equals</code> to the given value.
 @throws NullPointerException if the specified key or value is null
jctools-core/src/main/java/org/jctools/maps/NonBlockingIdentityHashMap.java