want '{}' but I give [] in response (seatbid and bid params) ?use python send protobuf openrtb data

[SchopenhauerZhang]

details address:https://groups.google.com/forum/#!search/protobuf$20openrtb$20$20|sort:date/protobuf/JCiZi3JVumc/gs61xoQ1BgAJ

in response ,I format data to protobuf in openrtb2.0 (proto2) and python 3.7. but the support team said the seatbid and bid attr 's value is [](array or list ) not '{}'.
how to change my code? the seatbid and bid attr is array(repeated) in proto file.