The CSS URL Mapping tool does not correctly parse data urls, such as:

background: url(data:image/svg+xml;base64,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);
    

And will process this in it's relative directory (ICEmobile skins in this case) as:

background-image: url("#{resource['org.icefaces.component.skins']}");