RenewalRound
data class RenewalRound(val group: LeaseGroup, val node: String, val leases: Int, val lost: Int, val failed: Int, val duration: Duration)
One renewal round of node in group: the leases it held, of which lost were found already expired or taken, or went unrenewed for leaseTtl − renewInterval, and failed threw, and how long the round took. A round longer than leaseTtl − renewInterval lets the node's own leases expire between renewals.