VOL-4740 : Fix match metadata in FTTB Subscriber downstream flows

Change-Id: I918dee6f006c1f26921250c90c7a40d8bcaf2131
diff --git a/impl/src/main/java/org/opencord/olt/impl/OltFlowService.java b/impl/src/main/java/org/opencord/olt/impl/OltFlowService.java
index 7a1cdc7..55d8964 100644
--- a/impl/src/main/java/org/opencord/olt/impl/OltFlowService.java
+++ b/impl/src/main/java/org/opencord/olt/impl/OltFlowService.java
@@ -1923,7 +1923,7 @@
                     port.number()), 0);
 
         } else if (serviceName.equals(FTTB_SERVICE_SUBSCRIBER_TRAFFIC)) {
-            selectorBuilder.matchMetadata(uti.getPonCTag().toShort());
+            selectorBuilder.matchMetadata(uti.getPonSTag().toShort());
             treatmentBuilder.writeMetadata(OltFlowServiceUtils.createMetadata(VlanId.ANY,
                     uti.getTechnologyProfileId(),
                     port.number()), 0);