onValidation should include the value that was validated

[job13er]

Since validation is an asynchronous action, there's no guarantee that the most recently received onValidation call corresponds to the most recently received onChange call. In practice, that may be true, but if one of the onValidation calls takes longer than another, it's possible that they could get out of sequence.

We should include a copy of the value that was validated as part of the ValidationResult object passed to onValidation.