I want to let my strategy to sleep, i.e. idle for a certain time in its thread.
How can I do it?
Thanks.

Java docs: https://java.sun.com/javase/6/docs/api/java/lang/Thread.html#sleep(long)

try {
    Thread.sleep(1000);
  } catch (InterruptedException e) {
    e.printStackTrace();
    // handle the exceptional condition properly
} 

Where 1000 means 1000 milliseconds, so if you want your thread to sleep for one second use 1000

All methods of IStrategy are called in the same thread. Therefore, the strategy will stop all other work until 10 seconds pass.
We should note that each strategy instance has a separate thread and other strategies will continue executing.

Do nothing and return is enough.