Use java_import_external() for maven artifacts to allow usage of web proxy

Change-Id: I5c116ce33d35e51174b14c5022a5a9f183d01ecd
diff --git a/lib/BUCK b/lib/BUCK
index 614f33d..73d96ee 100644
--- a/lib/BUCK
+++ b/lib/BUCK
@@ -1,4 +1,4 @@
-# ***** This file was auto-generated at Thu, 6 Sep 2018 17:55:24 GMT. Do not edit this file manually. *****
+# ***** This file was auto-generated at Thu, 6 Sep 2018 23:27:43 GMT. Do not edit this file manually. *****
 # ***** Use onos-lib-gen *****
 
 pass_thru_pom(