Added bid ID generation code

adapters/vastbidder/vastbidder.go

@@ -100,13 +100,19 @@ func (a *VASTBidder) MakeBids(internalRequest *openrtb2.BidRequest, externalRequ
 		}
 
 		// Bid.ID is made empty as its generated randomly in etree and fastXML
-		etreeResp := etreeParserResp
-		if etreeResp != nil {
-			for _, bid := range etreeResp.Bids {
+		if etreeParserResp != nil {
+			for _, bid := range etreeParserResp.Bids {
 				bid.Bid.ID = ""
 			}
 		}
-		etrrResp, _ := jsonutil.Marshal(etreeResp)
+		etrrResp, _ := jsonutil.Marshal(etreeParserResp)
+
+		// Bid.ID is made empty for comparision above, creating it again
+		if etreeParserResp != nil {
+			for _, bid := range etreeParserResp.Bids {
+				bid.Bid.ID = generateRandomID()
+			}
+		}
 
 		isVASTMismatch := false
 		if string(xmlResp) != string(etrrResp) {