Thanks for the link to the doc. I think it should be okay to include percentiles in Distribution given that it was intended to be extensible. As for the user facing Metrics API, there will be no changes unless we want to allow the user to specify custom percentiles aside from a set of defaults. (backward-compatible change)
*public static Distribution distribution(Class<?> namespace, String name, Collection<Double> percentiles) { return new DelegatingDistribution(MetricName.named(namespace, name), ...); }* The only breaking changes would possibly be on the runner side. Thanks, Ajo