@Override
  public int compare(E left, E right) {
    FieldName leftKey = left.getKey();
    FieldName rightKey = right.getKey();

    boolean caseSensitive = isCaseSensitive();
    if (caseSensitive) {
      return (leftKey.getValue()).compareTo(rightKey.getValue());
    } else {
      return (leftKey.getValue()).compareToIgnoreCase(rightKey.getValue());
    }
  }