@Test public void newFactory_sharingRemoteName() {

  BaggagePropagation.FactoryBuilder builder = newFactoryBuilder(B3Propagation.FACTORY);
  SingleBaggageField userName =
    SingleBaggageField.newBuilder(BaggageField.create("userName")).addKeyName("baggage").build();
  SingleBaggageField userId =
    SingleBaggageField.newBuilder(BaggageField.create("userId")).addKeyName("baggage").build();
  builder.add(userName);
  assertThatThrownBy(() -> builder.add(userId))
    .isInstanceOf(IllegalArgumentException.class)
    .hasMessage("Propagation key already in use: baggage");
}