During the construction of the NamedContributorsMapAdapter, each value adapter is called only once.

Closes gh-29640

Comment From: wilkinsona

@philwebb could you take a look at this one please? You mentioned on the issue that we'd need to be careful about backwards compatibility.

Comment From: philwebb

I think my original concern was that existing users might be relying on the dynamic adapter code. I've pushed the PR with a polish commit, but I think I'll change it a little more so that the adaption is done on first access rather than during construction.

Comment From: philwebb

Actually, on second thoughts, I think things are fine. We previously called the valueAdapter during construction to validate the result.

Thanks for the PR @terminux