The bug

It is not possible to bind any in-game actions to the act of moving the scroll wheel up or down, unlike with other mouse button inputs.

Rebindability would be expected due to the existence of scrolling in the hotbar (MC-268283).

How to reproduce

1. Enter they Key Binds menu
2. Click on a control to rebind it
3. Scroll up or down

Expected results

The game control in question would become bound to this specific movement of the scroll wheel.

Actual results

It is not.

Further notes

I do not have a mouse with a horizontal scroll wheel (e.g. A4Tech 4D, Logitech MX Master, and so on), however I believe horizontal scrolling to be affected in much the same way.