DelayedProvider dp = new DelayedProvider(provider1, 1500);
DelayedProvider dp2 = new DelayedProvider(provider2, 100);
dp.start();
dp2.start();
cs = (CheckService) context.getService(ref_cs);
assertTrue("Check invocation - 2", cs.check());
long end = System.currentTimeMillis();
System.out.println("delay = " + (end - begin));
assertTrue("Assert min delay", (end - begin) >= 100);
assertTrue("Assert max delay", (end - begin) <= 1000);
dp.stop();