If an operation passes in something like "enabled"=>"true" instead of "enabled"=>true for an AD whose type is BOOLEAN, validateAndSet should convert to BOOLEAN before storing and validateOperation should convert to boolean before returning.

Doing it for validateOperation isn't so obvious, but that method already converts strings to expressions if expression are supported, and also runs any ParameterCorrector, so the method isn't a simple read of the model, and this new behavior is consistent. The method javadoc needs to be updated anyway to better reflect what it does.

I don't propose to do anything complex here; e.g. descending into complex attributes.

I'm pretty sure there's already a JIRA for this but I can't find it.