[VOL-4442] grpc streaming connection monitoring

Change-Id: Id787e94cf28745d36e72f8ed2f5c316312714db4
diff --git a/protos/voltha_protos/onu_inter_adapter_service.proto b/protos/voltha_protos/onu_inter_adapter_service.proto
index 1b9243a..3b3d25d 100755
--- a/protos/voltha_protos/onu_inter_adapter_service.proto
+++ b/protos/voltha_protos/onu_inter_adapter_service.proto
@@ -12,9 +12,9 @@
 import "voltha_protos/health.proto";
 
 service OnuInterAdapterService {
-    // GetHealthStatus is used by an OnuInterAdapterService client to verify connectivity
-    // to the gRPC server hosting the OnuInterAdapterService service
-    rpc GetHealthStatus(common.Connection) returns (health.HealthStatus);
+    // GetHealthStatus is used by a OnuInterAdapterService client to detect a connection
+    // lost with the gRPC server hosting the OnuInterAdapterService service
+    rpc GetHealthStatus(stream common.Connection) returns (stream health.HealthStatus);
 
     rpc OnuIndication(inter_adapter.OnuIndicationMessage) returns (google.protobuf.Empty);
     rpc OmciIndication(inter_adapter.OmciMessage) returns (google.protobuf.Empty);