🔧 Type of changes

• new bid adapter
• bid adapter update
• new feature
• new analytics adapter
• new module
• module update
• bugfix
• documentation
• configuration
• dependency update
• tech debt (test coverage, refactorings, etc.)

Migrates the Yahoo Ads bidder (and its yssp / yahoossp / yahooAdvertising
aliases) from OpenRTB 2.5 to OpenRTB 2.6 on the wire. Three changes, in the
bidder and its Spring config:

1. HTTP header x-openrtb-version: 2.5 → 2.6 in
   src/main/java/org/prebid/server/bidder/yahooads/YahooAdsBidder.java.
2. Remove the in-bidder down-conversion. The bidder explicitly converted the
   request back to 2.5 before serializing it
   (conversionManager.convertFromAuctionSupportedVersion(bidRequest, OrtbVersion.ORTB_2_5)).
   That call is removed, along with the now-unused
   BidRequestOrtbVersionConversionManager dependency in the bidder and its
   YahooAdsConfiguration.
3. Legacy ext→top promotion for regs.{gpp, gpp_sid, coppa}. The old
   modifyRegs / resolveExtRegs block re-buried these (and gdpr/us_privacy)
   into regs.ext. It is replaced with promoteRegsExtToTopLevel: a field is
   promoted only when it is absent at top-level and present and well-formed in
   regs.ext, and a key is removed from regs.ext if and only if that field
   was promoted. Typed ext-only fields (gpc, dsa), unknown regs.ext
   properties, a value already present at top-level, and any of the three that
   could not be promoted (e.g. a malformed, non-textual gpp, or a gpp_sid
   array with a non-integer element) are all left in regs.ext untouched, so
   no value is silently dropped. The strip decision uses a single per-field
   signal, so it does not depend on whether a sibling field triggered the
   rebuild.

No publisher-facing config change is required bidder params (dcn, pos) are
unchanged, and bidder-config/yahooAds.yaml already declared ortb-version: "2.6".

Why

PBS-Java core up-converts every incoming request to its canonical 2.6 form
(BidRequestOrtb25To26Converter) before bidders run. The Yahoo bidder then
explicitly down-converted that back to 2.5 and re-buried
gpp / gpp_sid / coppa into regs.ext, and sent x-openrtb-version: 2.5.
Net effect: even fully 2.6-aware publishers had privacy/addressability fields
buried in .ext on the wire.

Removing the in-bidder down-conversion lets core's existing promotion reach the
wire. The new promoteRegsExtToTopLevel additionally promotes the three
regulatory fields that neither converter handles.

What this means for publishers

Non-regulatory 2.6 fields the bidder does not transform (e.g. device.sua,
user.kwarray, site/app.inventorypartnerdomain, content.network,
content.channel) pass through in whatever shape the publisher sent.

What changed

YahooAdsBidder.java bumps the header literal, removes the down-converter call
and dependency, and replaces the regs re-bury logic with
promoteRegsExtToTopLevel + gppToPromote / gppSidToPromote /
coppaToPromote (each returns the value to lift, or null) and
removePromotedKeys. The helpers operate on a toBuilder() copy of Regs
(the bidder already rebuilds the request per-impression), so they cannot affect
the request other bidders see.

Test plan

Automated

• mvn test -Dtest=YahooAdsBidderTest 29 unit tests pass. New cases cover:
  ext→top promotion, mixed publisher shapes (some fields top-level, some in
  ext), wrong-typed regs.ext values (no promotion), a malformed value left in
  ext while a sibling field promotes, a gpp_sid array with a non-integer
  element left in ext untouched, the same field present at both top-level and
  ext (ext copy left untouched), and the no-ext short-circuit.
• mvn test -Dtest=YahooAdsTest integration test passes against the
  updated 2.6 wire fixture.

End-to-end against the Yahoo Ads SSP

A build of this branch was run as a local PBS-Java process (not Docker) and
pointed at the Yahoo Ads SSP endpoint. For each scenario a request was POSTed to
/openrtb2/auction with ext.prebid.debug: 1, and the exact bytes the bidder
put on the wire were read back from ext.debug.httpcalls.yahooAds[*] (request
body + headers). Every outbound carried x-openrtb-version: 2.6 and the SSP
returned HTTP 200. Bid presence varies with demand and is not asserted here.

How to verify locally

mvn package -DskipTests
java -jar target/prebid-server.jar \
  --spring.config.additional-location=<your-config>.yaml

curl -s -X POST http://localhost:8080/openrtb2/auction \
  -H 'Content-Type: application/json' \
  -d @your-yahooAds-request.json \
  | jq '.ext.debug.httpcalls.yahooAds[0].requestheaders["x-openrtb-version"]'
# → ["2.6"]

Test fixture changes

• test-yahooads-bid-request.json (integration): expected outbound now carries
  regs.gpp / regs.gpp_sid / regs.gdpr at top-level (previously under
  regs.ext).
• YahooAdsBidderTest.java: header assertion 2.5 → 2.6; the
  "remove/overwrite regs ext" tests are replaced with promotion + passthrough
  tests described above.

Backward compatibility

No breaking changes.

• Bidder-param schema (dcn, pos) unchanged.
• Bid-response handling (makeBids) unchanged.
• 2.6-shape requests are forwarded without re-burying.
• Legacy 2.5-ext requests get the core-promoted fields plus gpp / gpp_sid /
  coppa at top-level; all other fields pass through unchanged in .ext.

Aliases

yssp, yahoossp and yahooAdvertising are declared as aliases of yahooAds
in bidder-config/yahooAds.yaml and share the same YahooAdsBidder instance,
so all alias codes send the 2.6 wire after this PR.

For contact: prebid-tech-team@yahooinc.com

Implemented with assistance from Claude Code.