code: public Boolean isWriteLocked(K token) {
  	RWLock<K> lock = locks.get(token);
  	if (lock == null) return null;
  	return lock.isWriteLocked();
      }
docs: Queries if the write lock is held by any thread on given lock token, returns null when lock with
  this token does not exists
  
  @param token name of the lock to check
  @return