@Test public void getAll() {

  assertThat(BaggageField.getAll(emptyContext))
    .containsExactly(REQUEST_ID, AMZN_TRACE_ID);
  try (Tracing tracing = Tracing.newBuilder().build();
       Scope ws = tracing.currentTraceContext().newScope(emptyContext)) {
    assertThat(BaggageField.getAll())
      .containsExactly(REQUEST_ID, AMZN_TRACE_ID);
  }
}