doubleclick protobuf file load to project

1，download protobuf file to local

wget https://developers.google.com/ad-exchange/rtb/downloads/openrtb-proto.txt

wget https://developers.google.com/ad-exchange/rtb/downloads/openrtb-adx-proto.txt

2，move to protofile

mv   openrtb-proto.txt  openrtb.proto

mv openrtb-adx-proto.txt openrtb_adx.proto

3,edit two protofile to same package

update   openrtb_adx.proto use  new package name "your self package name " not "com.google.doubleclick"

eg:  package openrtb;

4，generate to go file

protoc  --go_out=. openrtb.proto    openrtb_adx.proto

5,set protobuf exten field  example:

    if err := proto.SetExtension(&seatBidBid, openrtb.E_Bid, bidExt); err != nil {
        logger.Warn( exchange, " set impTrackers Error[", err, "]")
        return false
    }