Properties map that has its keySet ordered consistently (via the key's lexicographical ordering).
This is useful in environments where maps must stay the same order (e.g. for signature verification)
This does NOT support remove against the iterators / etc.
Now unsorted until the keyset or entryset is requested.
The class is unsynchronized.
The keySet() and entrySet() methods return ordered sets.
Others - such as the enumerations values(), keys(), propertyNames() - do not.