CORD-2870: Bypass DHCP leasequery without learning routes.

  Changes:
    * Add configuration flag to disable old leasequery routing/learning flow
    * Route leasequery (v4 and v6) responses to an originator
    * Fix NPE and BufferOverflow exceptions in Dhcp6LeaseQueryOption
    * Make Dhcp4/Dhcp6HandlerUtil classes static
    * Fix codestyle issues

Change-Id: Ic9e527d73a226e7f1f544dab9fb98398b85c5460
(cherry picked from commit 96a0d3408594ee2db90a7e50f8942ea71fe2e2bc)
diff --git a/apps/dhcprelay/src/main/java/org/onosproject/dhcprelay/DhcpRelayManager.java b/apps/dhcprelay/src/main/java/org/onosproject/dhcprelay/DhcpRelayManager.java
index cd4e3b5..2b404d9 100644
--- a/apps/dhcprelay/src/main/java/org/onosproject/dhcprelay/DhcpRelayManager.java
+++ b/apps/dhcprelay/src/main/java/org/onosproject/dhcprelay/DhcpRelayManager.java
@@ -56,15 +56,15 @@
 import org.onosproject.dhcprelay.api.DhcpRelayService;
 import org.onosproject.dhcprelay.api.DhcpServerInfo;
 import org.onosproject.dhcprelay.config.DefaultDhcpRelayConfig;
-import org.onosproject.dhcprelay.config.IgnoreDhcpConfig;
-import org.onosproject.dhcprelay.config.IndirectDhcpRelayConfig;
+import org.onosproject.dhcprelay.config.DhcpServerConfig;
 import org.onosproject.dhcprelay.config.EnableDhcpFpmConfig;
+import org.onosproject.dhcprelay.config.IndirectDhcpRelayConfig;
+import org.onosproject.dhcprelay.config.IgnoreDhcpConfig;
 import org.onosproject.dhcprelay.store.DhcpRecord;
 import org.onosproject.dhcprelay.store.DhcpRelayStore;
 import org.onosproject.dhcprelay.store.DhcpFpmPrefixStore;
 import org.onosproject.routing.fpm.api.FpmRecord;
 import org.onosproject.net.Device;
-import org.onosproject.dhcprelay.config.DhcpServerConfig;
 import org.onosproject.net.Host;
 import org.onosproject.net.config.Config;
 import org.onosproject.net.device.DeviceEvent;
@@ -206,7 +206,6 @@
             label = "Enable DhcpRelay Fpm")
     protected boolean dhcpFpmEnabled = false;
 
-
     private ScheduledExecutorService timerExecutor;
 
     protected DeviceListener deviceListener = new InternalDeviceListener();
@@ -321,7 +320,6 @@
             }
             v6Handler.setDhcpFpmEnabled(dhcpFpmEnabled);
         }
-
     }
 
     private static List<TrafficSelector> buildClientDhcpSelectors() {