Refactor protocol buffer to split models into different packages

Change-Id: I26152ba227ebe9afd871c6e501ccca17c49e1e4e
diff --git a/incubator/protobuf/models/src/main/proto/net/link/LinkDescriptionProto.proto b/incubator/protobuf/models/src/main/proto/net/link/LinkDescriptionProto.proto
new file mode 100644
index 0000000..d24545d
--- /dev/null
+++ b/incubator/protobuf/models/src/main/proto/net/link/LinkDescriptionProto.proto
@@ -0,0 +1,14 @@
+syntax = "proto3";
+option java_package = "org.onosproject.grpc.net.link.models";
+
+package net.link;
+
+import "net/ConnectPointProto.proto";
+import "net/link/LinkEnumsProto.proto";
+
+message LinkDescriptionProto {
+    net.ConnectPointProto src = 1;
+    net.ConnectPointProto dst = 2;
+    net.link.LinkTypeProto type = 3;
+    map<string, string> annotations = 4;
+}
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