VOL-4029 Fetch ONU stats on demand

Change-Id: I7248ab65f320858e9bdf9bdf6a60a27a734b8640
diff --git a/internal/pkg/core/openolt.go b/internal/pkg/core/openolt.go
index 34e681e..51ce314 100644
--- a/internal/pkg/core/openolt.go
+++ b/internal/pkg/core/openolt.go
@@ -431,6 +431,8 @@
 		switch reqType := request.GetRequest().GetRequest().(type) {
 		case *extension.GetValueRequest_OltPortInfo:
 			return handler.getOltPortCounters(ctx, reqType.OltPortInfo), nil
+		case *extension.GetValueRequest_OnuPonInfo:
+			return handler.getOnuPonCounters(ctx, reqType.OnuPonInfo), nil
 		default:
 			return errResp(extension.GetValueResponse_ERROR, extension.GetValueResponse_UNSUPPORTED), nil
 		}