public static String validateIndexName(@Nullable String indexName) {
    checkDbIdentifier(indexName, "Index name", INDEX_NAME_MAX_SIZE);
    return indexName;
  }
@Test
  public void validateIndexName_throws_IAE_when_index_name_contains_invalid_characters() {
    assertThatThrownBy(() -> validateIndexName("(not/valid)"))
      .isInstanceOf(IllegalArgumentException.class)
      .hasMessage("Index name must be lower case and contain only alphanumeric chars or '_', got '(not/valid)'");
  }