userAgent property
String userAgentread / write
Set and get the default value of the User-Agent header for all requests generated by this HttpClient. The default value is Dart/<version> (dart:io).
If the userAgent is set to null, no default User-Agent header will be added to each request.
© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dartlang.org/stable/1.24.3/dart-io/HttpClient/userAgent.html