SoapClient with Parameter ?wsdl should return wsdl File

When I create a SoapServer with an wsdl File, the call from the SoapClient with the query Parameter should retrun the wsdl file.

```
'UTF-8'
) );
$server->addFunction( array(
'getFoo',
'getBar',
) );
$server->handle();

function getByProductCode( $request )
{
return $request;
}

function getByProductGroups( $request )
{
return $request;
}
```

http://127.0.0.1service/index.php?wsdl -> no wsdl

Is it possible to fix this issue please? Our services are all building upon this feature.

Greetings Jan