code: @Override
     public String deriveViewId(final FacesContext context, final String rawViewId)
     {
        String canonicalViewId = new URLDuplicatePathCanonicalizer().canonicalize(rawViewId);
        return parent.deriveViewId(context, canonicalViewId);
     }
docs: Canonicalize the given viewId, then pass that viewId to the next ViewHandler in the chain.