Fix typo in API guidelines

PiperOrigin-RevId: 605000346
Change-Id: I50cb345be0de56ed322b52f4f8aa2cb8b966a750
diff --git a/api-guidelines/classes.md b/api-guidelines/classes.md
index 830b474..2c21ab8 100644
--- a/api-guidelines/classes.md
+++ b/api-guidelines/classes.md
@@ -11,7 +11,7 @@
 `ViewGroup` or even `View`, instead of `FrameLayout`).
 
 If you are tempted to override methods from the base class to throw
-`@UnsupportedOperationException`, reconsider which base class you are using.
+`UnsupportedOperationException`, reconsider which base class you are using.
 
 ### Use the base collections classes <a name="classes-collections"></a>