Revert "Revert "Suppress NewApi warnings for @SystemApi -> public APIs""

This reverts commit d654277abfa0abd1268acc6db1753536509e41c8.

Reason for revert: Re-landing changes not related to postsubmit failure

Change-Id: I72fd6b908deeb293f1f3a342f006515029972089
diff --git a/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java b/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
index e78e336..de13d42 100644
--- a/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
+++ b/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
@@ -23,6 +23,7 @@
 import static android.net.RouteInfo.RTN_UNREACHABLE;
 import static android.system.OsConstants.EBUSY;
 
+import android.annotation.SuppressLint;
 import android.net.INetd;
 import android.net.InterfaceConfigurationParcel;
 import android.net.IpPrefix;
@@ -213,6 +214,7 @@
         return failures;
     }
 
+    @SuppressLint("NewApi")
     private static String findNextHop(final RouteInfo route) {
         final String nextHop;
         switch (route.getType()) {