> Yes, maybe even validatedValue should have been exposed for parameter interpolation via {validatedValue} in the spec. 
Maybe and I know you don't like it.

> And one actually has to use {foo} instead of ${foo} to display foo if it is a constraint attribute. But I have to use ${foo} if foo is a custom attribute. To somone authoring the error messages file this might be confusing. 
Right, I wonder whether we would have been better off spec wise if we accepted a slight semantic change around $. It was really just ${amount} which was the border case. I must say, you almost convinced me.Of course we would need to include validatedValue and all custom parameters. In 4.2 we already did it for validated value. This should probably go into a separate issue though. 

> The other thing is the spec refers to things like {foo} as "message parameters", but the new method addMessageParameter() doesn't add message parameters as per that definition but it adds attributes to be bound into the EL context. So IMO we should add least adapt the name and/or documentation to clarify the behavior.

Good point. I was not quite happy with the name myself. Would _addMessageAttribute_ be better. And do we still need to change the method if we are going to allow {foo} as well?

I am surprised you already merged w/ these things still in the open. Did the discussion of last on the mailing list leave some impression on you?