tests/message_sizes/messages1.proto

enum MessageStatus {
    FAIL = 0;
    OK = 1;
};

message MessageInfo {
   required fixed32 msg_id = 1;
   optional fixed32 interface_id = 2;
}

message MessageResponseInfo {
   required fixed64 interface_id = 1;
   required fixed32 seq = 2;
   required fixed32 msg_id = 3;
}

message MessageHeader {
   required MessageInfo info = 1;
   optional MessageResponseInfo response_info = 2;
   optional MessageResponse response = 3;
}

message MessageResponse {
   required MessageStatus status = 1;
   required fixed32 seq = 2;
}