Support for setting priority/severity?

[openface]

We are attempting to setup fluentd to match on specific tags with the goal of sending the messages with specific severities/priorities.

This doesn't appear possible with fluent-plugin-syslog_rfc5424 because all of the messages are hardcoded to priority 14:
https://github.com/cloudfoundry/fluent-plugin-syslog_rfc5424/blob/main/lib/rfc5424/formatter.rb#L9

Is this correct, shouldn't there exist a way to set severity or priority using this plugin, or am I missing something?

Thanks!