serialization.html#general-class-types">Kryo
serializer</a>
instead
(<a href="https://issues.apache.org/jira/browse/FLINK-16729">FLINK-16729</a>). A
meaningful alternative strategy is to assume that, in a normal scenario,
no two discrepant events can have exactly the same timestamp and to turn
the window state into a <code>MapState&lt;Long, Transaction&gt;</code> type. You can use
<a href="//nightlies.apache.org/flink/flink-docs-release-1.11/dev/stream/side_output.html">side-outputs</a>
to collect and monit