Open Saml2AuthenticationRequestContext

Fixed gh-8356

saml2/saml2-service-provider/src/main/java/org/springframework/security/saml2/provider/service/authentication/Saml2AuthenticationRequestContext.java

@@ -29,13 +29,13 @@ import org.springframework.util.Assert;
  * @see Saml2AuthenticationRequestFactory#createRedirectAuthenticationRequest(Saml2AuthenticationRequestContext)
  * @since 5.3
  */
-public final class Saml2AuthenticationRequestContext {
+public class Saml2AuthenticationRequestContext {
 	private final RelyingPartyRegistration relyingPartyRegistration;
 	private final String issuer;
 	private final String assertionConsumerServiceUrl;
 	private final String relayState;
 
-	private Saml2AuthenticationRequestContext(
+	protected Saml2AuthenticationRequestContext(
 			RelyingPartyRegistration relyingPartyRegistration,
 			String issuer,
 			String assertionConsumerServiceUrl,