Port PR from PBS-Java: Add a warning for when targeting attributes are truncated

[cross-repo-issue-creation]

A PR was merged over on PBS-Java

• Add a warning for when targeting attributes are truncated prebid-server-java#4188
• timestamp: 2025-09-29T12:02:25Z

[osulzhenko]

The issue: when the host company specifies a very small targeting attribute truncation (for example, a length of 1), it can result in a situation where, despite receiving valid bids, the auction returns no targeting because mandatory keys are absent. This update adds a warning to notify the person investigating the issue about what’s happening.

[bsardo]

Discussed this in backlog. I suspect we could also use a warning in PBS-Go for this situation. In this scenario, if the truncation size is too small the produced targeting keys will be too short missing the required prefix needed to be of value.