code: public void handleChannelClosed(final Channel closed, final IOException e) {
          for(final ActiveOperationImpl<?, ?> activeOperation : activeRequests.values()) {
              if (activeOperation.getChannel() == closed) {
                  // Only call cancel, to also interrupt still active threads
                  activeOperation.getResultHandler().cancel();
              }
          }
      }
docs: Receive a notification that the channel was closed.
  
  This is used for the {@link ManagementClientChannelStrategy.Establishing} since it might use multiple channels.
  
  @param closed the closed resource
  @param e the exception which occurred during close, if any