[DISCUSS] Add a custom label on MetricReporter like PrometheusPushGatewayReporter's groupingKey

[jinhai wang]

Hi all

We need add some custom labels on MetricReporter. 
We can add groupingKey to PrometheusPushGatewayReporter in version 1.10, but 
not in PrometheusReporter.
Can we add several methods to the interface MetricReporter to support?



Best Regards

jinhai...@gmail.com