EntityId ignored in xml relying-party-registration

[micvm]

Describe the bug
The entityId specified for a relying-party-registration via xml namespace seems to be ignored and defaults to the metadata location.

To Reproduce
Define a relying party registration via xml and give an arbitrary name. Example

<sec:relying-party-registrations>
        <sec:relying-party-registration
                entity-id="MyEntityId"
                registration-id="some-registrationId"
                metadata-location="classpath:someIdpMetaDataFile.xml"
        >
        </sec:relying-party-registration>
</sec:relying-party-registrations>

Download the metadata generated via org.springframework.security.saml2.provider.service.web.Saml2MetadataFilter e.g. by accessing https://myhost/saml2/service-provider-metadata/{registration-id} and check the entityId. It does not correspond and, instead, is equal to the metadata URL (as defined in org.springframework.security.saml2.provider.service.registration.RelyingPartyRegistration.Builder class).

Expected behavior
EntityId in the metadata XML should be identical with the one indicated within the relying-party-registration.

[micvm]

I do not know if this helps but I noticed the Saml2LoginBeanDefinitionParser does not read the entity-id attribute unlike the other attributes defined within the relying-party-registration element.

[jzheaux]

Hi, @micvm, I believe you are correct. Are you interested in contributing a PR that fixes the issue?

It would be helpful if it were based on the 5.7.x branch -- where the bug was introduced -- and included a unit test that fails without your change and passes with it.

[micvm]

I can have a try but I am not familiar with the Spring SDK and internals. For example, I tried to launch gradle tasks and I get the following for branch 5.7.x:

Task :buildSrc:test

JavadocApiPluginITest > multiModuleApi() FAILED
    java.io.FileNotFoundException at JavadocApiPluginITest.java:33

ShowcaseITest > build() FAILED
    org.gradle.testkit.runner.UnexpectedBuildFailure at ShowcaseITest.java:30

110 tests completed, 2 failed, 3 skipped

Any idea how I could solve that?