@Test public void shallowCopy() {

  TraceContext context = TraceContext.newBuilder().traceId(1).spanId(2).debug(true)
    .extra(Collections.singletonList(1L)).build();
  assertThat(InternalPropagation.instance.shallowCopy(context))
    .isNotSameAs(context)
    .usingRecursiveComparison()
    .isEqualTo(context);
}