TBH. What's the point of adding "default" strategy that throws exception? Couldn't this be done here?
```php
if (null === $this->unmatchedRequestStrategy) {
    throw new UnmatchedRequestException(sprintf(
        'No handler found for the request %s %s',
        $request->getMethod(),
        $request->getUrl()
    ));
}

$this->unmatchedRequestStrategy->handle($request);