Side titles issue

```dart
Widget bottomTitles(double value, TitleMeta meta) {
final titles = ['Mn', 'Te', 'Wd', 'Tu', 'Fr', 'St', 'Su'];

final Widget text = Text(
titles[value.toInt()],
style: const TextStyle(
color: Color(0xff7589a2),
fontWeight: FontWeight.bold,
fontSize: 14,
),
);

return SideTitleWidget(
axisSide: meta.axisSide,
space: 16, //margin top
child: text,
);
}
```

If you use the value as index to get the side title if the values are same to two items doesn't it show the same side title ? How did you design the library to show unique side title for each index ?

Start with the provided bottomTitles callback and inspect how SideTitleWidget and side-title values are handled in the chart API. Reproduce the case with duplicate values, then clarify the expected behavior and document or test the supported way to provide unique titles; the issue does not name a file or existing test.

Written by the indexing model from the issue text.