Enforced Checkstyle rule to limit line length.

Maximum line length is 120 right now (but we might want to think about
reducing it further in the future).

I've fixed the existing lines we had that violated the rule.

Change-Id: I077d0c427d35e1c5033aab45ed3fbbbf1d106e89
diff --git a/src/main/java/net/onrc/onos/apps/proxyarp/ArpCache.java b/src/main/java/net/onrc/onos/apps/proxyarp/ArpCache.java
index 6216f59..39dc119 100644
--- a/src/main/java/net/onrc/onos/apps/proxyarp/ArpCache.java
+++ b/src/main/java/net/onrc/onos/apps/proxyarp/ArpCache.java
@@ -137,7 +137,8 @@
 
         if (arpEntry != null && arpEntry.getMacAddress().equals(macAddress)) {
             arpEntry.setTimeLastSeen(System.currentTimeMillis());
-            log.debug("The same ArpCache, ip {}, mac {}. Update local cache last seen time only.", ipAddress, macAddress);
+            log.debug("The same ArpCache, ip {}, mac {}. " +
+                    "Update local cache last seen time only.", ipAddress, macAddress);
         } else {
             arpCache.put(ipAddress, new ArpCacheEntry(macAddress));
             kvArpCache.forceCreate(ipAddress, macAddress.toBytes());