Added debug info to ArpHandler and priorities to RoutingPopulator

Change-Id: I079c5d50b12602ef620dbc6c5812d4508fa0b58d
diff --git a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/ArpHandler.java b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/ArpHandler.java
index 7f4bcb1..6d9171b 100644
--- a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/ArpHandler.java
+++ b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/ArpHandler.java
@@ -227,13 +227,11 @@
                 .setSourceMACAddress(targetMac.toBytes())
                 .setEtherType(Ethernet.TYPE_ARP).setPayload(arpReply);
 
-
-        HostId dstId = HostId.hostId(
-                MacAddress.valueOf(arpReply.getTargetHardwareAddress()),
-                vlanId);
+        MacAddress hostMac = MacAddress.valueOf(arpReply.getTargetHardwareAddress());
+        HostId dstId = HostId.hostId(hostMac, vlanId);
         Host dst = srManager.hostService.getHost(dstId);
         if (dst == null) {
-            log.warn("Cannot send ARP response to unknown device");
+            log.warn("Cannot send ARP response to host {}", dstId);
             return;
         }