ArgumentSuggestions#strings @NonNullable marking

[CypDasHuhn]

Description

The ArgumentSuggestions methods dont have non-nullability marked to them. This means in kotlin, one might think these are nullable, which they are not (NPE).

I'll probably impl this myself, just wanted to note it down. (It's more of an enhancement then a bug i think)

Expected code

No response

Extra details

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