A couple considerations: * The domain objects have a mix of mutable and immutable collections. Is that intentional, or could all them be changed to immutable ones? * In jclouds we try to avoid using `null`, and one of the important points is to avoid using it as a return value in public methods to express absence ([null is evil](http://code.google.com/p/guava-libraries/wiki/UsingAndAvoidingNullExplained)!). Could the methods like the `getByValue` (and others, if any) used in the enums be refactored to return an `Optional`?
Apart from this last comments, this PR lgtm! --- Reply to this email directly or view it on GitHub: https://github.com/jclouds/jclouds-labs-openstack/pull/22#issuecomment-23525580
