Don't make an interface default if it has defined capabilities.

Rationale: if an interface has defined capabilities, it means it was
configured by the OEM for a specific purpose. Such interfaces should not
be made available for server mode (e.g., tethering) because they would
no longer be available to serve that purpose.

Test: None
Change-Id: I84c5c77430ac818bef3ca79d68a0f81042b9cb63
diff --git a/service-t/src/com/android/server/ethernet/EthernetTracker.java b/service-t/src/com/android/server/ethernet/EthernetTracker.java
index 6405795..3e71093 100644
--- a/service-t/src/com/android/server/ethernet/EthernetTracker.java
+++ b/service-t/src/com/android/server/ethernet/EthernetTracker.java
@@ -269,6 +269,8 @@
                     + ", ipConfig: " + ipConfig);
         }
 
+        // TODO: do the right thing if the interface was in server mode: either fail this operation,
+        // or take the interface out of server mode.
         final IpConfiguration localIpConfig = ipConfig == null
                 ? null : new IpConfiguration(ipConfig);
         if (ipConfig != null) {
@@ -579,8 +581,8 @@
         }
         if (DBG) Log.i(TAG, "maybeTrackInterface: " + iface);
 
-        // TODO: avoid making an interface default if it has configured NetworkCapabilities.
-        if (mDefaultInterface == null) {
+        // Do not make an interface default if it has configured NetworkCapabilities.
+        if (mDefaultInterface == null && !mNetworkCapabilities.containsKey(iface)) {
             mDefaultInterface = iface;
         }