replaced ex with exception for easy code understanding

Author: Adagedo

spring-context/src/main/java/org/springframework/cache/interceptor/AbstractCacheInvoker.java

@@ -122,8 +122,8 @@ public CacheErrorHandler getErrorHandler() {
 		try {
 			return cache.retrieve(key);
 		}
-		catch (RuntimeException ex) {
-			getErrorHandler().handleCacheGetError(ex, cache, key);
+		catch (RuntimeException exception) {
+			getErrorHandler().handleCacheGetError(exception, cache, key);
 			return null;
 		}
 	}