the metadata document
Optionalwanted: string[]
the entityIDs to look for in an aggregate
ok with the entityID, endpoints, signing and encryption
certificates, NameID formats, the two signing flags, validUntil,
cacheDuration and whether it is signed; or ok: false and why
Parses a metadata document's SPSSODescriptor. Answers rather than throws.
An aggregate is read only for the one entity named in
wanted; a document with no SAML 2.0 SPSSODescriptor is refused.