static new HashMap<Class, Constructor> nuEmptyObject_cache;

static <A> A nuEmptyObject(Class<A> c) ctex {
  Constructor ctr;
  
  synchronized(nuEmptyObject_cache) {
    ctr = nuEmptyObject_cache.get(c);
    if (ctr == null) {
      nuEmptyObject_cache.put(c, ctr = nuEmptyObject_findConstructor(c));
      ctr.setAccessible(true);
    }
  }

  try {
    ret (A) ctr.newInstance();
  } catch (InstantiationException e) {
    if (empty(e.getMessage())
     fail("Can't instantiate " + className(c), e);  
  }
}

static Constructor nuEmptyObject_findConstructor(Class c) {
  for (Constructor m : c.getDeclaredConstructors())
    if (m.getParameterTypes().length == 0)
      ret m;
  fail("No default constructor declared in " + c.getName());
}