dca inputType select and options values

When I set a dca field to the inputType select I am able to define the key values. Due to a logic way I want something structured I'd like the select options to be some values, but the keys should be numeric 0 based.

As soon as this happens the Controller prepareforwidget function detects it as an associative array and doesn't use the keys I put in manually.

Why would Contao do that? That means a simple numeric list of values is not possible if it started at 0.

Or is there some way around that which I missed?