Error in WebService Java and glashfish, occurs with List <> and i can't deploit it

I'm here for help about a webservice error while i deploy it, i'm using netbeans 8.2 with jdk8 and glash fish 4.1.1, this is the error.

Grave:   Exception while loading the app      
Grave:   Undeployment failed for context /WebService_BuenosAires  
Grave:   Exception while loading the app : java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: java.lang.RuntimeException: Servlet web service endpoint '' failure

And it appears when i add the List<> function to my web services, this is my code:

/**
 * Web service operation
 */
@WebMethod(operationName = "listarEmpleado")
public List<Empleado> listarEmpleado() {
    try {
        return EmpDAO.listarEmpleados();
    } catch (SQLException ex) {
        Logger.getLogger(WebService_Principal.class.getName()).log(Level.SEVERE, null, ex);
    }
    return null;
}

sorry if i wrote something wrong, english it's not my mother language, and yes, i wrote in stackoverflow in my community, but no one answered me :( jaja
Thanks