java - Convert ISO 8601 Date to a Standard String Format

I am trying to convert a valid ISO 8601 string to a consistent format so that sort and search using simple lexicographical order is possible.

My application could receive a date/time in any of the following formats, for example:

2015-02-05T02:05:17.000+00:00
2015-02-05T02:05:17+00:00
2015-02-05T02:05:17Z

These all represent the same date/time and I would like to convert them all to a canonical form for storage, say:

2015-02-05T02:05:17.000Z

My first thought was to just parse them using a technique from Converting ISO 8601-compliant String to java.util.Date, and then convert back to the desired string, but this breaks down when dealing with less precise date/times, for example:

2015-02-05T02:05:17Z
2015-02-05T02:05Z
2015-02-05Z
2015-02Z
2015Z

The imprecision of these times should be preserved. They should not be converted to:

2015-02-05T00:00:00.000Z

I've looked Java 8 and Joda-Time, but they seem to want to treat everything as specific points in time, and can't model the imprecise nature or partial dates/times.

UPDATE:

Using Java 8, I can do:

OffsetDateTime dateTime = OffsetDateTime.parse("2015-02-05T02:05:17+00:00");
System.out.println(dateTime.toString());

which gives me:

2015-02-05T02:05:17Z

which is what I want, but:

OffsetDateTime dateTime = OffsetDateTime.parse("2015-02-05T02:05:17.000+00:00");
System.out.println(dateTime.toString());

also gives me:

2015-02-05T02:05:17Z

Notice that java has thrown away the millisecond precision. Specifying 000 is treated the same as not specifying anything, which doesn't seem quite right.