Refactoring file structure for protobufs.

Change-Id: I50daf100d54750f97158304d87813e67861b1422
diff --git a/incubator/protobuf/models/src/main/proto/DeviceEventProto.proto b/incubator/protobuf/models/src/main/proto/DeviceEventProto.proto
new file mode 100644
index 0000000..9cbbf60
--- /dev/null
+++ b/incubator/protobuf/models/src/main/proto/DeviceEventProto.proto
@@ -0,0 +1,16 @@
+syntax = "proto3";
+option java_package = "org.onosproject.grpc.net.models";
+
+
+import "DeviceProto.proto";
+import "DeviceEnums.proto";
+import "PortProto.proto";
+
+package Device;
+
+// Corresponds to org.onosproject.net.device.DeviceEvent.
+message DeviceNotification {
+    Device.DeviceProto device = 1;
+    Device.DeviceEventType deviceEventType = 2;
+    Port.PortProto port = 3;
+}
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