Refactor buck external dependencies

Change-Id: Ia4b99493407eb7d4e893804cba6b944f758f085e
diff --git a/providers/openflow/group/BUCK b/providers/openflow/group/BUCK
index c6a6f6d..6c3a325 100644
--- a/providers/openflow/group/BUCK
+++ b/providers/openflow/group/BUCK
@@ -1,5 +1,6 @@
 COMPILE_DEPS = [
     '//lib:CORE_DEPS',
+    '//lib:NETTY',
     '//lib:openflowj',
     '//protocols/openflow/api:onos-protocols-openflow-api',
     '//providers/openflow/flow:onos-providers-openflow-flow',