// Clean up again immediately.
        return 0L
      }

      earliestEvictableConnection != null -> {
        // A connection will be ready to evict soon.
        return earliestEvictableIdleAtNs + keepAliveDurationNs - now
      }

      inUseConnectionCount > 0 -> {
        // All connections are in use. It'll be at least the keep alive duration 'til we run again.