Some of the deprecated spring.security.saml2.relyingparty.registration.*.identityprovider.* properties are ignored

[wilkinsona]

With thanks to @Anubhav-2000 and @jvalkeal, as diagnosed in spring-projects/spring-security#12810, there are some situations where deprecated identityprovider properties are ignored. Consider this YAML:

spring:
  security:
    saml2:
      relyingparty:
        registration:
          adfs:
            identityprovider:
              entity-id: https://idp.example.com/issuer
              verification:
                credentials:
                  - certificate-location: "classpath:idp.crt"
              singlesignon:
                url: https://idp.example.com/issuer/sso
                sign-request: false

In this case the certificate location is ignored. This happens because the assertingparty properties that replaced identityprovider has a default non-null value of Verification. It and its empty List<Credential> is then used and the configured location of classpath:idp.crt is ignored.

Another symptom of this is that warnings are not logged about all of the deprecated properties. With the above YAML, the following is logged:

2023-03-09 09:59:22.213  WARN 69586 --- [           main] ml2RelyingPartyRegistrationConfiguration : Property 'spring.security.saml2.relyingparty.registration.identityprovider.adfs.entity-id' is deprecated, please use 'spring.security.saml2.relyingparty.registration.assertingparty.adfs.entity-id' instead
2023-03-09 09:59:24.152  WARN 69586 --- [           main] ml2RelyingPartyRegistrationConfiguration : Property 'spring.security.saml2.relyingparty.registration.identityprovider.adfs.singlesignon.url' is deprecated, please use 'spring.security.saml2.relyingparty.registration.assertingparty.adfs.singlesignon.url' instead
2023-03-09 09:59:25.123  WARN 69586 --- [           main] ml2RelyingPartyRegistrationConfiguration : Property 'spring.security.saml2.relyingparty.registration.identityprovider.adfs.singlesignon.sign-request' is deprecated, please use 'spring.security.saml2.relyingparty.registration.assertingparty.adfs.singlesignon.sign-request' instead