Acquire::HTTP::Proxy "http://[domainuser[:Password02#]@10.1.1.8:8080/";

Acquire::http::Proxy "http://domainuser:Password02#]@10.1.1.8:8080/";

Acquire::http::Proxy "http:/user@domain.com:Password02#]@10.1.1.8:8080/";

root@canonical:/etc/apt# apt-get update

  407  Proxy Authorization Required

Reading package lists... Done
W: The repository 'http://security.ubuntu.com/ubuntu xenial-security Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://za.archive.ubuntu.com/ubuntu xenial Release' does

Acquire::http::Proxy "http://user:password@10.1.1.8:8080";
Acquire::https::Proxy "http://user:password@10.1.1.8:8080";
Acquire::ftp::Proxy "http://user:password@10.1.1.8:8080";