class AbstractConfig {

    public Set<String> unused() {
        Set<String> keys = new HashSet<>(originals.keySet());
        keys.removeAll(used);
        return keys;
    }

    @SuppressWarnings("unchecked") public  AbstractConfig(ConfigDef definition, Map<?, ?> originals,  Map<String, ?> configProviderProps, boolean doLog);
    public  AbstractConfig(ConfigDef definition, Map<?, ?> originals);
    public  AbstractConfig(ConfigDef definition, Map<?, ?> originals, boolean doLog);

}