api: Trim leading/trailing spaces from comments

https://de.wikipedia.org/wiki/Spezial:Artikelr%C3%BCckmeldungen_v5/Koala/04f88a25857b4259bf04842b2b775073
is a comments concisting of 4 spaces, no content.
This should've been considered hidden (because of no content)

Change-Id: Ia07b4701731c324ff3752b7595d9d21530c3b6e5
Merge "api: Trim leading/trailing spaces from comments"