Port Floxis: New Adapter

[floxis-admin]

🔧 Type of changes

• new bid adapter

✨ Whats the context?

This PR ports the Floxis bid adapter from PBS-Go to PBS-Java. Floxis is an ad exchange; the adapter sends standard OpenRTB 2.x server-to-server bid requests to the Floxis exchange so PBS publishers can access Floxis demand. It is the Java counterpart of the in-review Go adapter prebid/prebid-server#4811.

Scope:

• Media types: banner, video, native, audio (declared for both app and site).
• OpenRTB 2.6; GPP supported. The incoming bid request body is forwarded unchanged.
• Cookie sync: redirect type.
• modifying-vast-xml-allowed: false.

🧠 Rationale behind the change

Bidder params (imp[].ext.prebid.bidder.floxis):

• seat (string, required, minLength 1) — the Floxis seat the publisher buys through; appended url-escaped to the endpoint as ?seat=.
• region (string, optional, enum us-e / eu / apac, default us-e) — selects the regional RTB host.

Endpoint routing uses a fixed allowlist map in adapter code (us-e → rtb-us-e.floxis.tech, eu → rtb-eu.floxis.tech, apac → rtb-apac.floxis.tech; unknown/empty → us-e), filled into the {{Host}} macro. Routing is never derived from a request-supplied hostname — satisfying the "no fully dynamic hostnames" requirement. seat/region are read from the first imp; the request body is forwarded unchanged (no caller-owned object is mutated).

Bid type resolution treats bid.mtype (OpenRTB 2.6) as authoritative (1/2/3/4 → banner/video/audio/native). When mtype is absent, a single-format imp resolves to that media type; a multi-format imp without mtype cannot be disambiguated and surfaces a badServerResponse, while other bids in the response continue to be processed.

gvlVendorID is intentionally omitted (vendor-id: 0) — Floxis is not currently registered in the IAB Global Vendor List.

🔎 New Bid Adapter Checklist

• verify email contact works
• NO fully dynamic hostnames
• geographic host parameters are NOT required
• direct use of HTTP is prohibited - implement an existing Bidder interface that will do all the job
• if the ORTB is just forwarded to the endpoint, use the generic adapter - the adapter is not a plain forward: it performs region-based host routing, url-escaped seat injection, and mtype/single-format bid-type resolution, so a dedicated adapter is warranted
• cover an adapter configuration with an integration test

🧪 Test plan

• FloxisBidderTest — 19 unit tests; JaCoCo reports 100% instruction/line and 95% branch coverage on FloxisBidder. Covers region resolution (us-e/eu/apac/default/unknown/null), url-escaping the seat, request-forwarded-unchanged, and the full getMediaTypeForBid matrix (mtype-authoritative for all four types, unsupported mtype, single-format fallback for all four, multi-format-needs-mtype, no-format, imp-not-found), plus per-bid error accumulation.
• FloxisTest integration test — exercises the full auction path against WireMock and validates the adapter configuration is reachable.
• mvn test (unit + IT) and mvn checkstyle:check pass locally.

🏎 Quality check

• Are your changes following our code style guidelines?
• Are there any breaking changes in your code? — No.
• Does your test coverage exceed 90%? — Yes (100% line, 95% branch on the bidder).
• Are there any erroneous console logs, debuggers or leftover code in your changes? — No.

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Companion Go adapter: prebid/prebid-server#4811. The corresponding prebid.github.io documentation PR is forthcoming.

Please add the do not port label per the porting guide (I do not have label permissions on this repo).