This check monitors the count of messages for each source of a Graylog
instance. It outputs the total number of messages and the average rate of
messages in a given timeframe. You can choose if the service is shown on the
queried Graylog host or the sidecar host.
Needs the datasource "Check state of Graylog" to be configured.
The name of the source.
One service is created for each source.