LIST [STREAMS|TABLES] EXTENDED and
DESCRIBE [sourceName] EXTENDED commands can be used to show the metrics.
|num-active-queries||The current number of active queries running in this engine|
|num-persistent-queries||Number of persistent queries running in this engine|
KsqlMetricsExtension is for developers to provide custom metrics that will be emitted along with the default KSQL engine JMX metrics.