code: @Override
  	public boolean containsValue(final Object value) {
  		lock.readLock().lock();
  		try {
  			return contains(value);
  		} finally {
  			lock.readLock().unlock();
  		}
  	}
docs: /*
  (non-Javadoc)
  
  @see java.util.Hashtable#containsValue(java.lang.Object)