tuscany generated wsdl: namespace prefix for the attribute "base" is missing

I have a problem when I let tuscany generate the wsdl for a service.
Namespace prefix for the attribute "base" is missing.

If I have an object that extends another object, the schema generated
should be:
...
<xs:complexType name="myObjChild">
<xs:complexContent>
<xs:extension base="tns:myObj">
...

but i got

...
<xs:complexType name="myObjChild">
<xs:complexContent>
<xs:extension base="myObj">
...