code: private void removeInterest(SelectableChannel channel, int operation) {
      SelectionKey key = channel.keyFor(selector);
  
      // Exception would be thrown if key is null or key is inValid
      // We do not need double check it ahead
      key.interestOps(key.interestOps() & (~operation));
    }
docs: Remove one operation interest on a SelectableChannel.
  The SelectableChannel has to be registered with Selector ahead.
  Otherwise, NullPointerExceptions would throw
  The key for SelectableChannel has to be valid.
  Otherwise, InvalidValid Exception would throw.
  
  @param channel the SelectableChannel to remove operation interest
  @param operation the interest to remove