Refactoring file structure for protobufs.

Change-Id: I50daf100d54750f97158304d87813e67861b1422
diff --git a/incubator/protobuf/models/src/main/proto/LinkEventProto.proto b/incubator/protobuf/models/src/main/proto/LinkEventProto.proto
new file mode 100644
index 0000000..be1ee41
--- /dev/null
+++ b/incubator/protobuf/models/src/main/proto/LinkEventProto.proto
@@ -0,0 +1,13 @@
+syntax = "proto3";
+option java_package = "org.onosproject.grpc.net.models";
+
+package Link;
+
+import "LinkProto.proto";
+import "LinkEnums.proto";
+
+// Corresponds to org.onosproject.net.link.LinkEvent.
+message LinkNotification {
+    Link.LinkEventType linkEventType = 2;
+    Link.LinkProto link = 3;
+}
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