The MqttAsyncClient needs a ScheduledExecutorService param for the constructor but only the functionality of a ExecutorService is needed. Other frameworks works more often with ExecutorService and ...

$ bb /tmp/repro.clj retTYpe: interface java.util.concurrent.ExecutorService ctxClass: null meth: public static java.util.concurrent.ExecutorService java.util.concurrent.Executors.newCachedThreadPool ( ...