Initialize OpenSAML in OpenSamlAssertingPartyMetadataRepository

Closes gh-16042

This commit adds a static initializer block to both OpenSaml4AssertingPartyMetadataRepository
and OpenSaml5AssertingPartyMetadataRepository. This ensures OpenSAML is initialized upon class
loading, preventing failures when methods like withMetadataLocation are invoked without prior
initialization.

saml2/saml2-service-provider/src/opensaml4Main/java/org/springframework/security/saml2/provider/service/registration/OpenSaml4AssertingPartyMetadataRepository.java

@@ -50,6 +50,7 @@ import org.springframework.core.io.ResourceLoader;
 import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.security.saml2.Saml2Exception;
+import org.springframework.security.saml2.core.OpenSamlInitializationService;
 import org.springframework.security.saml2.provider.service.registration.BaseOpenSamlAssertingPartyMetadataRepository.MetadataResolverAdapter;
 import org.springframework.util.Assert;
 
@@ -68,6 +69,10 @@ import org.springframework.util.Assert;
  */
 public final class OpenSaml4AssertingPartyMetadataRepository implements AssertingPartyMetadataRepository {
 
+	static {
+		OpenSamlInitializationService.initialize();
+	}
+
 	private final BaseOpenSamlAssertingPartyMetadataRepository delegate;
 
 	/**

saml2/saml2-service-provider/src/opensaml4Test/java/org/springframework/security/saml2/provider/service/registration/OpenSaml4AssertingPartyMetadataRepositoryTests.java

@@ -53,7 +53,6 @@ import org.w3c.dom.Element;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.security.saml2.Saml2Exception;
-import org.springframework.security.saml2.core.OpenSamlInitializationService;
 import org.springframework.security.saml2.core.TestSaml2X509Credentials;
 import org.springframework.security.saml2.provider.service.authentication.TestOpenSamlObjects;
 
@@ -71,10 +70,6 @@ import static org.mockito.Mockito.withSettings;
  */
 public class OpenSaml4AssertingPartyMetadataRepositoryTests {
 
-	static {
-		OpenSamlInitializationService.initialize();
-	}
-
 	private static MetadataDispatcher dispatcher = new MetadataDispatcher()
 		.addResponse("/entity.xml", readFile("test-metadata.xml"))
 		.addResponse("/entities.xml", readFile("test-entitiesdescriptor.xml"));

saml2/saml2-service-provider/src/opensaml5Main/java/org/springframework/security/saml2/provider/service/registration/OpenSaml5AssertingPartyMetadataRepository.java

@@ -50,6 +50,7 @@ import org.springframework.core.io.ResourceLoader;
 import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.security.saml2.Saml2Exception;
+import org.springframework.security.saml2.core.OpenSamlInitializationService;
 import org.springframework.security.saml2.provider.service.registration.BaseOpenSamlAssertingPartyMetadataRepository.MetadataResolverAdapter;
 import org.springframework.util.Assert;
 
@@ -68,6 +69,10 @@ import org.springframework.util.Assert;
  */
 public final class OpenSaml5AssertingPartyMetadataRepository implements AssertingPartyMetadataRepository {
 
+	static {
+		OpenSamlInitializationService.initialize();
+	}
+
 	private final BaseOpenSamlAssertingPartyMetadataRepository delegate;
 
 	/**

saml2/saml2-service-provider/src/opensaml5Test/java/org/springframework/security/saml2/provider/service/registration/OpenSaml5AssertingPartyMetadataRepositoryTests.java

@@ -53,7 +53,6 @@ import org.w3c.dom.Element;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.security.saml2.Saml2Exception;
-import org.springframework.security.saml2.core.OpenSamlInitializationService;
 import org.springframework.security.saml2.core.TestSaml2X509Credentials;
 import org.springframework.security.saml2.provider.service.authentication.TestOpenSamlObjects;
 
@@ -71,10 +70,6 @@ import static org.mockito.Mockito.withSettings;
  */
 public class OpenSaml5AssertingPartyMetadataRepositoryTests {
 
-	static {
-		OpenSamlInitializationService.initialize();
-	}
-
 	private static MetadataDispatcher dispatcher = new MetadataDispatcher()
 		.addResponse("/entity.xml", readFile("test-metadata.xml"))
 		.addResponse("/entities.xml", readFile("test-entitiesdescriptor.xml"));