private function findNonExistingUserEmail( $username = 'User' )
    {
        $userManager = $this->getUserManager();
        $email = "${username}@ez.no";
        if ( $userManager->checkUserExistenceByEmail( $email ) )
        {
            return $email;
        }

        for ( $i = 0; $i < 20; $i++ )
        {
            $email = uniqid('User#', true) . '@ez.no';
            if ( !$userManager->checkUserExistenceByEmail( $email ) )
            {
                return $email;
            }
        }

        throw new \Exception( 'Possible endless loop when attempting to find a new email for User.' );
    }