public static NameMapping of(MappedField... fields) {
    return new NameMapping(MappedFields.of(ImmutableList.copyOf(fields)));
  }
@Test
  public void testAllowsDuplicateNamesInSeparateContexts() {
    new NameMapping(
        MappedFields.of(
            MappedField.of(1, "x", MappedFields.of(MappedField.of(3, "x"))),
            MappedField.of(2, "y", MappedFields.of(MappedField.of(4, "x")))));
  }