protected function validateWebspaceDefaultSegment()
    {
        // check if there are duplicate defaults in the webspaces segments
        $segments = $this->webspace->getSegments();
        if ($segments) {
            $webspaceDefaultSegmentFound = false;
            foreach ($segments as $webspaceSegment) {
                if ($webspaceSegment->isDefault()) {
                    // throw an exception, if a new default segment is found, although there already is one
                    if ($webspaceDefaultSegmentFound) {
                        throw new InvalidWebspaceDefaultSegmentException($this->webspace);
                    }
                    $webspaceDefaultSegmentFound = true;
                }
            }

            if (!$webspaceDefaultSegmentFound) {
                throw new WebspaceDefaultSegmentNotFoundException($this->webspace);
            }
        }
    }