missing link for gNMI stub

Change-Id: I86b106f59414b528b027c5b55173915106f99dd0
diff --git a/protocols/pom.xml b/protocols/pom.xml
index a231ce9..84c0a1c 100644
--- a/protocols/pom.xml
+++ b/protocols/pom.xml
@@ -44,6 +44,7 @@
         <module>restconf</module>
         <module>tl1</module>
         <module>grpc</module>
+        <module>gnmi/stub</module>
         <module>p4runtime</module>
         <module>xmpp</module>
     </modules>