@Test public void localRootId_nextSpan_sampled() {

  TraceContext context1 = TraceContext.newBuilder().traceId(1).spanId(2).sampled(true).build();
  TraceContext context2 = TraceContext.newBuilder().traceId(1).spanId(3).sampled(true).build();
  localRootId(context1, context2, ctx -> tracer.nextSpan(ctx));
}