[ONOS-7233] Add MastershipRole protobuf model with translators

Change-Id: I02168e91d45c61593a02702b7a05a9810424a2c2
diff --git a/incubator/protobuf/models/src/main/proto/cluster/RoleInfoProto.proto b/incubator/protobuf/models/src/main/proto/cluster/RoleInfoProto.proto
new file mode 100644
index 0000000..44dfdaa
--- /dev/null
+++ b/incubator/protobuf/models/src/main/proto/cluster/RoleInfoProto.proto
@@ -0,0 +1,11 @@
+syntax = "proto3";
+option java_package = "org.onosproject.grpc.cluster.models";
+
+import "cluster/NodeIdProto.proto";
+
+package cluster;
+
+message RoleInfoProto {
+    cluster.NodeIdProto master = 1;
+    repeated cluster.NodeIdProto backups = 2;
+}
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