Change TetheringConstants class to final

Bug: 151322331
Test: m doc-comment-check-docs
Change-Id: Ia02be3d1d91a08ae4a56b25560ed448c96a693db
diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringConstants.java b/Tethering/common/TetheringLib/src/android/net/TetheringConstants.java
index a18f5da..fd6f171 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringConstants.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringConstants.java
@@ -32,7 +32,7 @@
  * @hide
  */
 @SystemApi(client = MODULE_LIBRARIES)
-public class TetheringConstants {
+public final class TetheringConstants {
     /** An explicit private class to avoid exposing constructor.*/
     private TetheringConstants() { }