Fix a flake with mocking.

The hypothesis here is that some other thread is using
the mock between the call to when() and the call to
.thenReturn() a few lines above the failure. It's not
clear this is really the reason, but using this syntax
is safer anyway, so whether it fixes the issue or not
this is a good change.

Test: m FrameworksNetTests
Change-Id: I501d2ec8e794c67a53d7c84e290e4cc63481472d
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index e28f3c4..8382317 100644
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -1529,7 +1529,7 @@
     }
 
     private <T> T doAsUid(final int uid, @NonNull final Supplier<T> what) {
-        when(mDeps.getCallingUid()).thenReturn(uid);
+        doReturn(uid).when(mDeps).getCallingUid();
         try {
             return what.get();
         } finally {
@@ -9860,9 +9860,9 @@
         assertVpnUidRangesUpdated(true, vpnRange, vpnOwnerUid);
 
         final UnderlyingNetworkInfo underlyingNetworkInfo =
-                new UnderlyingNetworkInfo(vpnOwnerUid, VPN_IFNAME, new ArrayList<String>());
+                new UnderlyingNetworkInfo(vpnOwnerUid, VPN_IFNAME, new ArrayList<>());
         mMockVpn.setUnderlyingNetworkInfo(underlyingNetworkInfo);
-        when(mDeps.getConnectionOwnerUid(anyInt(), any(), any())).thenReturn(42);
+        doReturn(42).when(mDeps).getConnectionOwnerUid(anyInt(), any(), any());
     }
 
     private void setupConnectionOwnerUidAsVpnApp(int vpnOwnerUid, @VpnManager.VpnType int vpnType)