Events received Rate expression using metricbeat on Timelion

Hello?

I wanna draw Events received Rates per second on Kibana timelion using metricbeat :slight_smile:

Is this right expressions for this purpose?

.es(
index=test-monitoring*,
timefield='@timestamp',
q='event.module:kafka AND _exists_:kafka.partition.offset.newest',
metric='avg:event.duration').multiply(0.000000001).label('Duration(sec) of Newest Events') 

I'm curious about the common field event.duration of metricbeat.
Is this duration of events received on kafka(or each modules) or metricbeat side ?

It's ambiguous in the documentation: https://www.elastic.co/guide/en/beats/metricbeat/current/exported-fields-ecs.html#_event_3