@Test public void noFields_newFactory_disallowed() {

  assertThatThrownBy(() -> ExtraFieldPropagation.newFactory(B3Propagation.FACTORY))
    .hasMessage("no field names");
  assertThatThrownBy(() -> ExtraFieldPropagation.newFactory(B3Propagation.FACTORY, asList()))
    .hasMessage("no field names");
}