NullPointerException in ServiceClient

[Ryo Neyama <ne...@trl.ibm.co.jp>]

The following code doesn't work as I expected but it throws
NullPointerException.
SOAPEnvelope reqEnv = ...;
ServiceClient call = new ServiceClient(url);
SOAPEnvelope respEnv = call.invoke(reqEnv);

This is caused by the following code in ServiceClient.
    public SOAPEnvelope invoke(SOAPEnvelope env) throws AxisFault
    {
        msgContext.reset();
        msgContext.setRequestMessage(new Message(env));
        invoke();
        return msgContext.getResponseMessage().getAsSOAPEnvelope();
    }

More specifically, msgContext.reset() removed the url set in the
constructor.

Is this a bug or spec?
If it's spec, why?

    Ryo Neyama @ IBM Research, Tokyo Research Laboratory
    Internet Technology
    neyama@trl.ibm.co.jp