Look's like it's really enforced by JAX-WS 2.2 spec. In Conformance Requirements in 2.7 Service and Port there's:

Conformance (Generated service (URL,QName,WebServiceFeature...) constructor): The implemen-
tation class MUST have a public constructor that takes three arguments, the WSDL location (a java-
.net.URL ), the service name (a javax.xml.namespace.QName ) and the web service features (a varargs
javax.xml.ws.WebServiceFeature ). This constructor MUST call the javax.xml.ws.Service(URL,
QName, WebServiceFeature ...) protected constructor, passing as arguments the WSDL location, the
service name and the web service feature values with which it was invoked.