Request: Better documentation for PersistentStateComponent

Some things (off the top of my head) that should be documented:

1) Which data types can be serialized by default?

2) Is no-arg constructor always required? Is there a way to get around without a no-arg constructor?

3) Is MapAnnotation always required for maps? Example of how to use it. 

4) When is AbstractCollection annotation required? 

5) When is Tag annotation required?