assertTrue(tracer.traces.get(traceId).size() == 1);
assertEquals("shortest trace ever", tracer.traces.get(traceId).get(0).description);
Span pause = Trace.start("pause");
Thread.sleep(100);
pause.stop();
assertTrue(tracer.traces.get(traceId).size() == 2);
assertTrue(tracer.traces.get(traceId).get(1).millis() >= 100);
Thread t = new Thread(Trace.wrap(new Runnable() {
@Override