General

Restructure mechanism factories into validateFor and populateFor rather than being split between factory, engine and mechanism
- It looks like all that should really be needed is a single mechanism and a convention
Turn coercion engine into a mechanism/convention like anything else
Naming is currently all over the place
Consider having the convention return an attribute populator which knows how to perform population for that attribute
Hints for particular types when one population mechanism is preferred. Maybe annotations?
Work out how to remove conditional logic into some sort of polymorphism instead

Builder

Add problem reporting when wither expects different types to what can be constructed from the provided value
Add recursion support

Bean

Everything

Constructor

Is this possible? Annotations maybe?

Direct Field

Add problem reporting
Add iterable support
Add recursion support