static Map<Class, Constructor> nuEmptyObject_cache = newDangerousWeakHashMap();

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));
      makeAccessible(ctr);
    }
  }

  try {
    ret (A) ctr.newInstance();
  } catch (InstantiationException e) {
    if (empty(e.getMessage()))
      if ((c.getModifiers() & Modifier.ABSTRACT) != 0)
        fail("Can't instantiate abstract class " + className(c), e);
      else
        fail("Can't instantiate " + className(c), e);  
    else throw rethrow(e);
  }
}

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

Began life as a copy of #1001136