Warning about metrics.gauge

[sferry]

Hi,
I run logstash 7.5.1-1.
I just saw in the log :
[2020-02-28T11:37:27,088][WARN ][org.logstash.instrument.metrics.gauge.LazyDelegatingGauge][main] A gauge metric of an unknown type (org.jruby.specialized.RubyArrayOneObject) has been create for key: cluster_uuids. This may result in invalid serialization. It is recommended to log an issue to the responsible developer/development team.

So I pass on the recommendation to warn responsible/dev team.
Cheers
Sophie