Avoid repeated superclass introspection in AnnotationUtils.findAnnotation

--- C:\Project\AnnotationUtils.java	2018-04-16 16:16:04.974657900 -0400
+++ C:\Project\src\main\java\org\springframework\core\annotation\AnnotationUtils.java	2018-03-12 16:58:54.540000000 -0400

@@ -136,6 +148,14 @@
 			new ConcurrentReferenceHashMap<Method, AliasDescriptor>(256);
 
 	private static transient Log logger;
+	
+	private static final Annotation NULL_ANNOTATION = new Annotation() {
+
+		@Override
+		public Class<? extends Annotation> annotationType() {
+			// TODO Auto-generated method stub
+			return null;
+		}};
 
 
 	/**
@@ -558,13 +578,14 @@
 	@SuppressWarnings("unchecked")
 	public static <A extends Annotation> A findAnnotation(Method method, Class<A> annotationType) {
 		Assert.notNull(method, "Method must not be null");
+		
 		if (annotationType == null) {
 			return null;
 		}
 
 		AnnotationCacheKey cacheKey = new AnnotationCacheKey(method, annotationType);
 		A result = (A) findAnnotationCache.get(cacheKey);
-
+		
 		if (result == null) {
 			Method resolvedMethod = BridgeMethodResolver.findBridgedMethod(method);
 			result = findAnnotation((AnnotatedElement) resolvedMethod, annotationType);
@@ -595,9 +616,13 @@
 			if (result != null) {
 				result = synthesizeAnnotation(result, method);
 				findAnnotationCache.put(cacheKey, result);
+			}else {
+				findAnnotationCache.put(cacheKey, NULL_ANNOTATION);
 			}
 		}
-
+		if(NULL_ANNOTATION == result) {
+			result = null;
+		}
 		return result;
 	}
 
@@ -691,8 +716,13 @@
 			if (result != null && synthesize) {
 				result = synthesizeAnnotation(result, clazz);
 				findAnnotationCache.put(cacheKey, result);
+			}else if(result == null && synthesize) {
+				findAnnotationCache.put(cacheKey, NULL_ANNOTATION);
 			}
 		}
+		if(NULL_ANNOTATION == result) {
+			result = null;
+		} 
 		return result;
 	}