public static void sleep(long millis) {
		try {
			Thread.sleep(millis);
		} catch (InterruptedException e) {
			throw new UncheckedInterruptedException(e);
		}
	}
Sleep in give millis without throwing exception.

@param millis	millisecond.
ngrinder-core/src/main/java/org/ngrinder/common/util/ThreadUtils.java