wp-includes/class-wp-http-proxy.php:114Retrieve the username for proxy authentication.
string public function username() { if ( defined( 'WP_PROXY_USERNAME' ) ) { return WP_PROXY_USERNAME; } return ''; }Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-http-proxy.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.