Provide support for validating embedded lists

Lists of Objects that are embedded into a domain object do not support validators, due to incompatible types.

When the embedded object is also a Domain object, any validators of the child are ignored. It would be ideal if there was a way to enable the validators of the embedded child objects.

The issue names no files, tests, or entry points. Start by locating how validation handles embedded lists of domain objects and where incompatible types cause child validators to be ignored. Done means validators defined on embedded child objects are applied when the parent domain object is validated.

Written by the indexing model from the issue text.