public ScopedSpan startScopedSpan(String name) {
    return startScopedSpanWithParent(name, currentTraceContext.get());
  }
@Test void startScopedSpan() {
    ScopedSpan scoped = tracer.startScopedSpan("foo");
    try {
      assertThat(tracer.currentTraceContext.get()).isSameAs(scoped.context());
    } finally {
      scoped.finish();
    }

    assertThat(spans.get(0).name())
      .isEqualTo("foo");
    assertThat(spans.get(0).finishTimestamp())
      .isPositive();
  }