framework/web/GroupUrlRule.php
public function init()
    {
        $this->prefix = trim($this->prefix, '/');
        $this->routePrefix = $this->routePrefix === null ? $this->prefix : trim($this->routePrefix, '/');
        parent::init();
    }
public function init()
    {
        $this->prefix = trim($this->prefix, '/');
        $this->routePrefix = $this->routePrefix === null ? $this->prefix : trim($this->routePrefix, '/');
        parent::init();
    }
{@inheritdoc}