In fact, the resume is made automatically when you complete the task.
For example,
CommandBasedWSHumanTaskHandler handler = new CommandBasedWSHumanTaskHandler(ksession)
...
handler.connect()
..
session.registerWorkItemHandler("Human Task", handler);
This will make that:
1) The human task listeners for task completion are registered.
2) When task is registered, the listener has the session to continue the process.
Now, you can make
client.complete(taskId,...)
Now the listener (you can check it, GetResultContentResponseHandler) will be notified about task completion and process continued.
Hope this helps,
Demian