Suspending a Process Instance using Runtime Service

I have a Async Service Task, I got the instance of RunTimeService from the context and tried this

RuntimeService runtimeService = Context.getProcessEngineConfiguration().getRuntimeService();
   Boolean isSuspended =  runtimeService.createProcessInstanceQuery().processInstanceId(execution.getProcessInstanceId()).singleResult().isSuspended();
   if(!isSuspended) {

But the process seems to be continuing to next event/activity in the BPM model.
How is it possible to achieve actual suspension of a process Instance

See How to Suspend A Process Instance using Service Task