Put registration id in validation error message

Closes gh-42278

Author: mhalbritter

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientProperties.java

@@ -31,6 +31,7 @@
  * @author Phillip Webb
  * @author Artsiom Yudovin
  * @author MyeongHyeon Lee
+ * @author Moritz Halbritter
  * @since 2.0.0
  */
 @ConfigurationProperties(prefix = "spring.security.oauth2.client")
@@ -60,12 +61,12 @@ public void afterPropertiesSet() {
 	}
 
 	public void validate() {
-		getRegistration().values().forEach(this::validateRegistration);
+		getRegistration().forEach(this::validateRegistration);
 	}
 
-	private void validateRegistration(Registration registration) {
+	private void validateRegistration(String id, Registration registration) {
 		if (!StringUtils.hasText(registration.getClientId())) {
-			throw new IllegalStateException("Client id must not be empty.");
+			throw new IllegalStateException("Client id of registration '%s' must not be empty.".formatted(id));
 		}
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesTests.java

@@ -37,7 +37,7 @@ void clientIdAbsentThrowsException() {
 		registration.setProvider("google");
 		this.properties.getRegistration().put("foo", registration);
 		assertThatIllegalStateException().isThrownBy(this.properties::validate)
-			.withMessageContaining("Client id must not be empty.");
+			.withMessageContaining("Client id of registration 'foo' must not be empty.");
 	}
 
 	@Test