update method
Implementation
void update(int code, String result, String header, int size) {
_code = code;
_result = result;
_header = header;
this.size = size;
endTimestamp = DateTime.now().millisecondsSinceEpoch;
var kit = ApmKitManager.instance.getKit(ApmKitName.kitHttp) as HttpKit?;
kit?.listener?.call();
}