Feature Request: API: allow the IN operator on the text attribute type.

[Thijzer]

This feature Request is simply based on the fact that when a akeneo catalog has a GTIN or EAN attribute field(s).
I like to search on those fields with the IN operator.

Currently
Often GTIN or EAN codes are decorated in the PIM as text attributes with the Uniqueness flag on.
So it would be nice to have support for that IN operator in these cases.

Ideally
Ideally it should be better to define GTIN or EAN codes as additional (sub) identifiers where we can query on. What they truly are
and what makes it easier for suppliers to add their identifier to your pim.