hook_system_breadcrumb_alter contains an unnecessary by reference notation

The hook hook_system_breadcrumb_alter is documented like this:

function hook_system_breadcrumb_alter(\Drupal\Core\Breadcrumb\Breadcrumb &$breadcrumb, \Drupal\Core\Routing\RouteMatchInterface $route_match, array $context) {

This is unnecessary, as objects (Breadcrumb object in this case) are always passed by reference. This, in turn, ends up in hook_implementations automatically if you are using phpstorm for example.

Let's remove &