public DeduplicateTableBuilder setIdentityColumn(String identityColumn) {
    this.identityColumn = identityColumn;
    return this;
  }
@Test
  public void build_shouldThrowException_whenReferenceColumnUndefined(){
    DeduplicateTableBuilder builder = new DeduplicateTableBuilder("example_table")
      .setIdentityColumn("identity_column");

    Assertions.assertThatThrownBy(builder::build).isInstanceOf(IllegalArgumentException.class)
      .hasMessage("At least one reference column must be specified");
  }