public static Schema createEnum(String name, String doc, String namespace, List<String> values) {
    return new EnumSchema(new Name(name, namespace), doc, new LockableArrayList<>(values), null);
  }
@Test
  void enumSymbolAsNull() {
    assertThrows(SchemaParseException.class, () -> {
      Schema.createEnum("myField", "doc", "namespace", Collections.singletonList(null));
    });
  }