* @return <code>null</code> if the callee fails to create one.
     *
     * @throws NullPointerException
     *      If the <code>schemaLanguage</code> parameter is null.
     */
    public SchemaFactory newFactory(String schemaLanguage) {
        if(schemaLanguage==null)        throw new NullPointerException();
        SchemaFactory f = _newFactory(schemaLanguage);
        if (f != null) {
            debugPrintln("factory '" + f.getClass().getName() + "' was found for " + schemaLanguage);
        } else {
            debugPrintln("unable to find a factory for " + schemaLanguage);
        }
        return f;
    }