"refactor -> extract interface" refactoring looks to me like a feature that
helps users/developers to separate the interface contract from the
implementation and it works correctly for java classes.

 In webservices area (JAX-WS 2.0) such contract is defined in a little bit
different way (that's why I filed this as a bug - at looks to me like "broken"
feature, but feel free to change this to RFE if you disagree). Example will say
more, so if I have following ws:

package test;
@WebService
public class MyServiceImpl {

    @WebMethod(operationName="sayHello")
    public String test(@WebParam(name="to") String p) {
        return "Hello " + p;
    }
}

then after "Refactor -> extract interface" invoked on such class I would expect
to have (or at least optionaly be able to have) "changed" impl. class like this
(note that there's no "implements" part):

package test;
@WebService(enpointInterface="test.MyWebservice")
public class MyServiceImpl {

    public String test(String p) {
        return "Hello " + p;
    }
}

and this new interface exctracted from base class:

package test;
@WebService
public interface MyService {

    @WebMethod(operationName="sayHello")
    String test(@WebParam(name="to") String p);
}