Do not remove trailing slash from OAuth2 Issuer URI

Fixes gh-15324

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesRegistrationAdapter.java

@@ -86,9 +86,7 @@ public final class OAuth2ClientPropertiesRegistrationAdapter {
 			Provider provider = providers.get(providerId);
 			String issuer = provider.getIssuerUri();
 			if (issuer != null) {
-				String cleanedIssuer = cleanIssuerPath(issuer);
+				Builder builder = ClientRegistrations.fromOidcIssuerLocation(issuer)
-				Builder builder = ClientRegistrations
-						.fromOidcIssuerLocation(cleanedIssuer)
 						.registrationId(registrationId);
 				return getBuilder(builder, provider);
 			}
@@ -96,13 +94,6 @@ public final class OAuth2ClientPropertiesRegistrationAdapter {
 		return null;
 	}
 
-	private static String cleanIssuerPath(String issuer) {
-		if (issuer.endsWith("/")) {
-			return issuer.substring(0, issuer.length() - 1);
-		}
-		return issuer;
-	}
-
 	private static Builder getBuilder(String registrationId, String configuredProviderId,
 			Map<String, Provider> providers) {
 		String providerId = (configuredProviderId != null) ? configuredProviderId

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesRegistrationAdapterTests.java

@@ -269,8 +269,7 @@ public class OAuth2ClientPropertiesRegistrationAdapterTests {
 		this.server = new MockWebServer();
 		this.server.start();
 		String issuer = this.server.url("").toString();
-		String cleanIssuerPath = cleanIssuerPath(issuer);
+		setupMockResponse(issuer);
-		setupMockResponse(cleanIssuerPath);
 		OAuth2ClientProperties.Registration registration = new OAuth2ClientProperties.Registration();
 		registration.setProvider("okta-oidc");
 		registration.setClientId("clientId");
@@ -297,7 +296,7 @@ public class OAuth2ClientPropertiesRegistrationAdapterTests {
 		assertThat(adapted.getAuthorizationGrantType())
 				.isEqualTo(AuthorizationGrantType.AUTHORIZATION_CODE);
 		assertThat(adapted.getRegistrationId()).isEqualTo("okta");
-		assertThat(adapted.getClientName()).isEqualTo(cleanIssuerPath);
+		assertThat(adapted.getClientName()).isEqualTo(issuer);
 		assertThat(adapted.getScopes()).containsOnly("user");
 		assertThat(adapted.getRedirectUriTemplate())
 				.isEqualTo("http://example.com/redirect");
@@ -316,8 +315,7 @@ public class OAuth2ClientPropertiesRegistrationAdapterTests {
 		this.server = new MockWebServer();
 		this.server.start();
 		String issuer = this.server.url("").toString();
-		String cleanIssuerPath = cleanIssuerPath(issuer);
+		setupMockResponse(issuer);
-		setupMockResponse(cleanIssuerPath);
 		OAuth2ClientProperties properties = new OAuth2ClientProperties();
 		Provider provider = new Provider();
 		provider.setIssuerUri(issuer);
@@ -332,7 +330,7 @@ public class OAuth2ClientPropertiesRegistrationAdapterTests {
 		assertThat(adapted.getAuthorizationGrantType())
 				.isEqualTo(AuthorizationGrantType.AUTHORIZATION_CODE);
 		assertThat(adapted.getRegistrationId()).isEqualTo("okta");
-		assertThat(adapted.getClientName()).isEqualTo(cleanIssuerPath);
+		assertThat(adapted.getClientName()).isEqualTo(issuer);
 		assertThat(adapted.getScopes()).containsOnly("openid");
 		assertThat(providerDetails.getAuthorizationUri())
 				.isEqualTo("https://example.com/o/oauth2/v2/auth");

spring-boot-samples/spring-boot-sample-oauth2-client/src/main/resources/application.yml

@@ -29,4 +29,4 @@ spring:
             client-name: GitHub Repositories
         provider:
           yahoo-oidc:
-            issuer-uri: https://api.login.yahoo.com/
+            issuer-uri: https://api.login.yahoo.com

spring-boot-samples/spring-boot-sample-reactive-oauth2-client/src/main/resources/application.yml

@@ -22,4 +22,4 @@ spring:
             client-secret: ${YAHOO-CLIENT-SECRET}
         provider:
           yahoo-oidc:
-            issuer-uri: https://api.login.yahoo.com/
+            issuer-uri: https://api.login.yahoo.com