Saml2RelyingPartyRegistrationConfiguration can choose the wrong RelyingPartyRegistration.Builder when using a metadata file with multiple providers

[lasselindqvist]

Saml2RelyingPartyRegistrationConfiguration chooses the wrong RelyingPartyRegistration.Builder when using a metadata file with multiple providers. It always just chooses the first one it finds, when it actually should chooses the one with the correct entity-id.

The method now is:

	private RelyingPartyRegistration asRegistration(String id, Registration properties) {
		AssertingPartyProperties assertingParty = new AssertingPartyProperties(properties, id);
		boolean usingMetadata = StringUtils.hasText(assertingParty.getMetadataUri());
		Builder builder = (usingMetadata)
				? RelyingPartyRegistrations.fromMetadataLocation(assertingParty.getMetadataUri()).registrationId(id)
				: RelyingPartyRegistration.withRegistrationId(id);
....

when it could be for example:

	private RelyingPartyRegistration asRegistration(String id, Registration properties) {
		AssertingPartyProperties assertingParty = new AssertingPartyProperties(properties, id);
		boolean usingMetadata = StringUtils.hasText(assertingParty.getMetadataUri());
		Builder builder = (usingMetadata)
				? RelyingPartyRegistrations.collectionFromMetadataLocation(assertingParty.getMetadataUri())
				.stream().filter(builder -> properties.getEntityId().equals(builder.build().getEntityId()))
				.registrationId(id)
				: RelyingPartyRegistration.withRegistrationId(id);
....

This can be tested with metadata files that have multiple providers, such as https://virtu-ds.csc.fi/fed/virtu/virtu-metadata-v7.xml

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[philwebb]

Thanks very much @lasselindqvist, this is now in 2.7.x and merged forward to 3.0.x, 3.1.x and 3.2.x,