[SP01] Add NetworkStats to system API

In order to let external module report their network stats,
expose necessary APIs to construct NetworkStats object.

Test: atest FrameworksNetTests CtsUsageStatsTestCases
Test: m doc-comment-check-docs
Bug: 130855321
Change-Id: Id3ec8aaff3df67948c25eac2319a74cf33a27979
diff --git a/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java b/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java
index 38fa91e..ce7c2a6 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java
@@ -279,7 +279,7 @@
                 entry.iface = kv.getKey();
                 entry.rxBytes = value.rxBytes;
                 entry.txBytes = value.txBytes;
-                stats.addValues(entry);
+                stats.addEntry(entry);
             }
 
             return stats;