Enable broker-side timestamp override

This seems to be due to an the obsolete Kafka message format used by
afkak producer in VOLTHA

Change-Id: I7e454c1727d7d3b0bff40e9bfd5ae848591370b0
diff --git a/examples/kafka-production.yaml b/examples/kafka-production.yaml
index 135130b..399edf2 100644
--- a/examples/kafka-production.yaml
+++ b/examples/kafka-production.yaml
@@ -25,6 +25,18 @@
 configurationOverrides:
   "offsets.topic.replication.factor": 3
   "log.retention.hours": 4
+  "log.message.timestamp.type": "LogAppendTime"
+
+# NOTE: The log.message.timestamp.type override causes timestamps set by the
+# producer be overridden on the broker. This should be removed once all kafka
+# libraries have been updated to use the newer v1 message format that add the
+# timestamp to the message.
+#
+# The `afkak` client in VOLTHA uses the outdated format, and reports -1 as the
+# timestamp.
+#
+# More context:
+#  https://cwiki.apache.org/confluence/display/KAFKA/KIP-32+-+Add+timestamps+to+Kafka+message
 
 replicas: 3