class Configuration implements Iterable<Map.Entry<String,String>>,
                                      Writable {

  public Class<?> getClass(String name, Class<?> defaultValue) {
    String valueString = getTrimmed(name);
    if (valueString == null)
      return defaultValue;
    try {
      return getClassByName(valueString);
    } catch (ClassNotFoundException e) {
      throw new RuntimeException(e);
    }
  }

  public  Configuration();
  public  Configuration(boolean loadDefaults);
  @SuppressWarnings("unchecked") public  Configuration(Configuration other);

}