AspectJExpressionPointcut leniently ignores non-composable interfaces

Issue: SPR-17003

spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJExpressionPointcut.java

@@ -433,9 +433,15 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 			// Note: AspectJ is only going to take Method.getDeclaringClass() into account.
 			Set<Class<?>> ifcs = ClassUtils.getAllInterfacesForClassAsSet(targetClass);
 			if (ifcs.size() > 1) {
-				Class<?> compositeInterface = ClassUtils.createCompositeInterface(
-						ClassUtils.toClassArray(ifcs), targetClass.getClassLoader());
-				targetMethod = ClassUtils.getMostSpecificMethod(targetMethod, compositeInterface);
+				try {
+					Class<?> compositeInterface = ClassUtils.createCompositeInterface(
+							ClassUtils.toClassArray(ifcs), targetClass.getClassLoader());
+					targetMethod = ClassUtils.getMostSpecificMethod(targetMethod, compositeInterface);
+				}
+				catch (IllegalArgumentException ex) {
+					// Implemented interfaces probably expose conflicting method signatures...
+					// Proceed with original target method.
+				}
 			}
 		}
 		return getShadowMatch(targetMethod, method);

spring-core/src/main/java/org/springframework/util/ClassUtils.java

@@ -771,6 +771,8 @@ public abstract class ClassUtils {
 	 * @param interfaces the interfaces to merge
 	 * @param classLoader the ClassLoader to create the composite Class in
 	 * @return the merged interface as Class
+	 * @throws IllegalArgumentException if the specified interfaces expose
+	 * conflicting method signatures (or a similar constraint is violated)
 	 * @see java.lang.reflect.Proxy#getProxyClass
 	 */
 	@SuppressWarnings("deprecation")