Rubicon Bidder: Add Bid Meta Seat Field

src/main/java/org/prebid/server/bidder/rubicon/RubiconBidder.java

@@ -1617,19 +1617,27 @@ private List<BidderBid> bidsFromResponse(BidRequest prebidRequest,
     }
 
     private RubiconSeatBid updateSeatBids(RubiconSeatBid seatBid, List<BidderError> errors) {
-        final String buyer = seatBid.getBuyer();
-        final int networkId = NumberUtils.toInt(buyer, 0);
-        if (networkId <= 0) {
+        final Integer networkId = resolveNetworkId(seatBid);
+        final String seat = seatBid.getSeat();
+
+        if (networkId == null && seat == null) {
             return seatBid;
         }
+
         final List<RubiconBid> updatedBids = seatBid.getBid().stream()
-                .map(bid -> insertNetworkIdToMeta(bid, networkId, errors))
+                .map(bid -> prepareBidMeta(bid, seat, networkId, errors))
                 .filter(Objects::nonNull)
                 .toList();
         return seatBid.toBuilder().bid(updatedBids).build();
     }
 
-    private RubiconBid insertNetworkIdToMeta(RubiconBid bid, int networkId, List<BidderError> errors) {
+    private static Integer resolveNetworkId(RubiconSeatBid seatBid) {
+        final String buyer = seatBid.getBuyer();
+        final int networkId = NumberUtils.toInt(buyer, 0);
+        return networkId <= 0 ? null : networkId;
+    }
+
+    private RubiconBid prepareBidMeta(RubiconBid bid, String seat, Integer networkId, List<BidderError> errors) {
         final ObjectNode bidExt = bid.getExt();
         final ExtPrebid<ExtBidPrebid, ObjectNode> extPrebid;
         try {
@@ -1640,9 +1648,13 @@ private RubiconBid insertNetworkIdToMeta(RubiconBid bid, int networkId, List<Bid
         }
         final ExtBidPrebid extBidPrebid = extPrebid != null ? extPrebid.getPrebid() : null;
         final ExtBidPrebidMeta meta = extBidPrebid != null ? extBidPrebid.getMeta() : null;
-        final ExtBidPrebidMeta updatedMeta = meta != null
-                ? meta.toBuilder().networkId(networkId).build()
-                : ExtBidPrebidMeta.builder().networkId(networkId).build();
+
+        final ExtBidPrebidMeta updatedMeta = Optional.ofNullable(meta)
+                .map(ExtBidPrebidMeta::toBuilder)
+                .orElseGet(ExtBidPrebidMeta::builder)
+                .networkId(networkId)
+                .seat(seat)
+                .build();
 
         final ExtBidPrebid modifiedExtBidPrebid = extBidPrebid != null
                 ? extBidPrebid.toBuilder().meta(updatedMeta).build()

src/main/java/org/prebid/server/proto/openrtb/ext/response/ExtBidPrebidMeta.java

@@ -67,4 +67,6 @@ public class ExtBidPrebidMeta {
     @JsonProperty("secondaryCatIds")
     List<String> secondaryCategoryIdList;
 
+    String seat;
+
 }

src/test/java/org/prebid/server/bidder/rubicon/RubiconBidderTest.java

@@ -3305,6 +3305,34 @@ public void makeBidsShouldReplaceNotPresentAdmWithAdmNative() throws JsonProcess
                 .containsExactly("{\"admNativeProperty\":\"admNativeValue\"}");
     }
 
+    @Test
+    public void makeBidsShouldSetSeatToMetaSeat() throws JsonProcessingException {
+        // given
+        final BidderCall<BidRequest> httpCall = givenHttpCall(
+                givenBidRequest(identity()),
+                mapper.writeValueAsString(RubiconBidResponse.builder()
+                        .cur("USD")
+                        .seatbid(singletonList(RubiconSeatBid.builder()
+                                .seat("seat")
+                                .bid(singletonList(givenRubiconBid(bid -> bid.price(ONE))))
+                                .build()))
+                        .build()));
+
+        // when
+        final Result<List<BidderBid>> result = target.makeBids(httpCall, givenBidRequest(identity()));
+
+        // then
+        final ObjectNode expectedBidExt = mapper.valueToTree(
+                ExtPrebid.of(ExtBidPrebid.builder()
+                        .meta(ExtBidPrebidMeta.builder().seat("seat").build())
+                        .build(), null));
+        assertThat(result.getErrors()).isEmpty();
+        assertThat(result.getValue())
+                .extracting(BidderBid::getBid)
+                .extracting(Bid::getExt)
+                .containsExactly(expectedBidExt);
+    }
+
     @Test
     public void makeBidsShouldSetSeatBuyerToMetaNetworkId() throws JsonProcessingException {
         // given