Java callout - terminate processes

[tchelets]

Hi, 
In my Java callout, I starts a new thread by 

ScheduledExecutorService executorService = Executors.newSingleThreadScheduledExecutor();

I added the `close()` function of the `AutoCloseable` Interface.
even though the API Proxy was undeployed,  the thread is still running.
what is the way to terminate running threads in the Java code so that the undeploy API Proxy will affect its termination?