question: void notifyFailure ( Throwable exception ) { synchronized ( waitObject ) { isComplete = true ; if ( exception instanceof MqttException ) { pendingException = ( MqttException ) exception ; } else { pendingException = new MqttException ( exception ) ; } waitObject . notifyAll ( ) ; if ( exception instanceof MqttException ) { lastException = ( MqttException ) exception ; } if ( listener != null ) { listener . onFailure ( this , exception ) ; } } }
target:  notify unsuccessful completion of the operation