Port PR from PBS-Go: RTB House: Remove PAAPI signals from imp[].ext

[cross-repo-issue-creation[bot]]

A PR was merged over on PBS-Go

• https://github.com/prebid/prebid-server/pull/4399
• timestamp: 2025-07-24T16:10:34Z

[AntoxaAntoxic]

Looks like the PBS Java and PBS Go have slight discrepancies in the core logic regarding what fields should be treated as bidderparams.

That Go PR mentions 3 fields, that should be cleaned up for the RTBHouse Bidder: ae, igs, paapi.

On the Java side the first one ae is a reserved by the core, so it works as expected and should be cleared manually for the imp[].ext.ae path. The igs and paapi fields are not reserved as bidder params by default, so the client has to mention them in the ext.prebid.bidderparams. And if some fields are mentioned in the ext.prebid.bidderparams they will be moved to the imp[].ext.bidder so the clean-up happening for the imp[].ext might not really clean paapi and igs since they are not there at first place.

At the same time if the igs and paapi fields are not declared as bidderparams the request validation won't fail the request but will remove those fields with a warning since they are treated as the non-existing bidder names. Technically those fields will be cleaned up on the core level, so the request to the bidder won't contain any of those fields. But the client will see a weird warning with the message like "the bidder igs has been dropped as unknown".

It's a little bit unclear what is the best way to implement it on the Java side. @Net-burst Do you have any thought on that?