Created LinkService and added unit tests.

Change-Id: I1f2104c873e5a9e2df34074d36cddc823e3b3ec5
diff --git a/incubator/protobuf/models/src/main/proto/net/ProviderIdProto.proto b/incubator/protobuf/models/src/main/proto/net/ProviderIdProto.proto
new file mode 100644
index 0000000..3e470c7
--- /dev/null
+++ b/incubator/protobuf/models/src/main/proto/net/ProviderIdProto.proto
@@ -0,0 +1,11 @@
+syntax = "proto3";
+option java_package = "org.onosproject.grpc.net.models";
+
+package net;
+
+// Corresponds to org.onosproject.net.provider.ProviderId
+message ProviderIdProto {
+    string scheme = 1;
+    string id = 2;
+    bool ancillary = 3;
+}
\ No newline at end of file