static ColumnExtractor create(final Column column) {
    final int index = column.index();
    Preconditions.checkArgument(index >= 0, "negative index: " + index);

    return column.namespace() == Namespace.KEY
        ? new KeyColumnExtractor(index)
        : new ValueColumnExtractor(index);
  }
@Test(expected = IllegalArgumentException.class)
  public void shouldThrowOnNegativeIndex() {
    // Given:
    when(column.index()).thenReturn(-1);

    // When:
    TimestampColumnExtractors.create(column);
  }