Log RetryException for @Retryable methods

To improve diagnostics, this commit logs a DEBUG message including the
RetryException thrown by RetryTemplate when it's used behind the scenes
for @Retryable method invocations.

Closes gh-35983

spring-context/src/main/java/org/springframework/resilience/retry/AbstractRetryInterceptor.java

@@ -22,6 +22,8 @@ import java.util.concurrent.Future;
 
 import org.aopalliance.intercept.MethodInterceptor;
 import org.aopalliance.intercept.MethodInvocation;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
@@ -50,6 +52,8 @@ import org.springframework.util.ClassUtils;
  */
 public abstract class AbstractRetryInterceptor implements MethodInterceptor {
 
+	private static final Log logger = LogFactory.getLog(AbstractRetryInterceptor.class);
+
 	/**
 	 * Reactive Streams API present on the classpath?
 	 */
@@ -102,6 +106,7 @@ public abstract class AbstractRetryInterceptor implements MethodInterceptor {
 				.maxDelay(spec.maxDelay())
 				.build();
 		RetryTemplate retryTemplate = new RetryTemplate(retryPolicy);
+		String methodName = ClassUtils.getQualifiedMethodName(method, (target != null ? target.getClass() : null));
 
 		try {
 			return retryTemplate.execute(new Retryable<@Nullable Object>() {
@@ -112,11 +117,14 @@ public abstract class AbstractRetryInterceptor implements MethodInterceptor {
 				}
 				@Override
 				public String getName() {
-					return ClassUtils.getQualifiedMethodName(method, (target != null ? target.getClass() : null));
+					return methodName;
 				}
 			});
 		}
 		catch (RetryException ex) {
+			if (logger.isDebugEnabled()) {
+				logger.debug("@Retryable operation '%s' failed".formatted(methodName), ex);
+			}
 			throw ex.getCause();
 		}
 	}