A DCQL feature to match elements in an array?

[danielfett]

In this commit I introduced the contains filter that can be used to check if an array contains one or more specified values. I later removed it again since it didn't seem to be a good fit for the scope of the PR.

However, having such a feature would allow to express certain queries that are impossible to express at the moment ("give me all nationalities if one of them is 'JP'").

This issue is for tracking if we still need a contains-like filter or not.

[c2bo]

Also came up in several IIW discussions - I would say there seems to be interest in this feature