Transport: Fix NTCP removing IPv4 address when SSU removes IPv6 address

router/java/src/net/i2p/router/transport/CommSystemFacadeImpl.java

@@ -323,21 +323,19 @@ public class CommSystemFacadeImpl extends CommSystemFacade {
         if (ip != null || port > 0)
             _manager.externalAddressReceived(Transport.AddressSource.SOURCE_SSU, ip, port);
         else
-            notifyRemoveAddress(false);
+            notifyRemoveAddress(udpAddr);
     }
 
     /** 
      *  Tell other transports our address changed
      *
-     *  @param address non-null; but address's host/IP may be null
+     *  @param address may be null; or address's host/IP may be null
      *  @since 0.9.20
      */
     @Override
     public void notifyRemoveAddress(RouterAddress address) {
         // just keep this simple for now, multiple v4 or v6 addresses not yet supported
-        notifyRemoveAddress(address != null &&
-                            address.getIP() != null &&
-                            address.getIP().length == 16);
+        notifyRemoveAddress(address != null && TransportUtil.isIPv6(address));
     }
 
     /** 

router/java/src/net/i2p/router/transport/TransportUtil.java

@@ -124,6 +124,8 @@ public abstract class TransportUtil {
     /**
      *  Addresses without a host (i.e. w/introducers)
      *  are assumed to be IPv4 unless a '6' cap is present
+     *
+     *  @param addr non-null
      */
     public static boolean isIPv6(RouterAddress addr) {
         // do this the fast way, without calling getIP() to parse the host string