The private class EmptyList of java.util.Collections could override iterator
and perhaps improve performance of the enhanced for loop.

Simply add this to the class:

private static Iterator<?> iterator = new Iterator() {
    public boolean hasNext() { return false; }
    public Object next() { throw new NoSuchElementException(); }
    public void remove() { throw new UnsupportedOperationException(); }
}
public Iterator iterator() { return iterator; }