code: @SuppressWarnings("unchecked")
  	public static ConnectionObserver connectionObserver(AbstractBootstrap<?, ?> b) {
  		Objects.requireNonNull(b, "bootstrap");
  		ConnectionObserver obs =
  				(ConnectionObserver) b.config()
  				                             .options()
  				                             .get(OBSERVER_OPTION);
  		if (obs == null) {
  			return ConnectionObserver.emptyListener(); //will not be triggered in
  		}
  		b.option(OBSERVER_OPTION, null);
  		return obs;
  	}
docs: Obtain and remove the current {@link ConnectionObserver} from the bootstrap.
  
  @param b the bootstrap to scan
  
  @return current {@link ConnectionObserver} or null