@Override
  public boolean isNull(final int columnIndex) {
    return getValue(columnIndex) == null;
  }
@Test
  public void shouldReturnNull() {
    assertThat(row.isNull("f_null"), is(true));
    assertThat(row.isNull("f_bool"), is(false));
    assertThat(row.isNull("f_struct"), is(false));
  }