### Question:
Duration extends TimeBase<Duration> { @Override public Duration subtract(Duration d) { return new Duration(this.toSec() - d.toSec()); } Duration();  Duration(int secs, int nsecs);  Duration(double sec);  Duration(long nano); @Override Duration add(Duration d); @Override Duration subtract(Duration d); boolean sleep(); @Override Duration clone(); static Duration fromSec(double sec); static Duration fromNano(long nano); static Duration fromJsonString(String jsonString); static Duration fromJsonObject(JsonObject jsonObject); static final String TYPE; }### Answer:
@Test public void testSubtract() { assertEquals(new Duration(9999998996l), d3.subtract(d2)); assertEquals(d1, d1.subtract(empty)); assertEquals(d2, d2.subtract(empty)); assertEquals(d3, d3.subtract(empty)); }