Refactoring file structure for protobufs.

Change-Id: I50daf100d54750f97158304d87813e67861b1422
diff --git a/incubator/protobuf/models/src/main/proto/LinkProto.proto b/incubator/protobuf/models/src/main/proto/LinkProto.proto
new file mode 100644
index 0000000..2355618
--- /dev/null
+++ b/incubator/protobuf/models/src/main/proto/LinkProto.proto
@@ -0,0 +1,18 @@
+syntax = "proto3";
+option java_package = "org.onosproject.grpc.net.models";
+
+package Link;
+
+import "LinkEnums.proto";
+import "ConnectPointProto.proto";
+
+// Corresponds to org.onosproject.net.Link.
+message LinkProto {
+    Link.LinkState state = 1;
+    ConnectPoint.ConnectPoint src = 2;
+    ConnectPoint.ConnectPoint dst = 3;
+    Link.LinkType type = 4;
+    map<string, string> annotations = 5;
+}
+
+