Growl error 303 with growlNotify task

I've noticed that when you wrote a growl notify task with generic code like that : 

    <growlnotify name="${notify.growl-name}"
        sticky="${notify.growl-sticky}"
        message="${notify.growl-message}"
        title="${notify.growl-title}"
        notification="${notify.growl-notification}"
        appicon="${notify.growl-appicon}"
        host="${notify.growl-host}"
        password="${notify.growl-password}"
        priority="${notify.growl-priority}"
        protocol="${notify.growl-protocol}"
        icon="${notify.growl-icon}"
    />

And when of these values are empty (blank) , then the Growl client return an error 303 (required header missing).

This patch fixed the issue, without to change growlNotify task behaviors or features.

- Laurent