### Question:
Time extends TimeBase<Time> { public static boolean sleepUntil(Time t) { return Duration.fromSec(t.subtract(Time.now()).toSec()).sleep(); } Time();  Time(int secs, int nsecs);  Time(double sec);  Time(long nano); @Override Time add(Time t); @Override Time subtract(Time t); boolean isValid(); Date toDate(); static boolean sleepUntil(Time t); @Override Time clone(); static Time now(); static Time fromSec(double sec); static Time fromNano(long nano); static Time fromDate(Date date); static Time fromJsonString(String jsonString); static Time fromJsonObject(JsonObject jsonObject); static final String TYPE; }### Answer:
@Test public void testSleepUntil() { Time t = new Time(((double) System.currentTimeMillis() + 500) / 1000.0); assertTrue(Time.sleepUntil(t)); assertTrue(greaterThanEquals(System.currentTimeMillis(), t.toDate() .getTime())); }