Chaining MetadataProvider and IdPv3

[Rod Widdowson]

> 1)  Why was the Chaining MetadataProvider type brought forward to IdPv3?
> Config compatibility, other?  

Compatibility, particularly in old-style relying party configurations (plus
I added it before we realized we could get right of the need).

> Is it still mandatory?

ISTR that old style relying party needs it.

> 2)  Is there any functional difference between having a Chaining element
> wrapped around two providers and having multiple EntityDescriptors beyond
> the modest control provided by the MetadataProvider configuration itself?

I'm not sure I understand the question.  But I can tell you that all that
happens if the parser meets multiple metadata providers is that it grows an
implicit chaining provider and inserts it.

Rod