Once started, NWPathMonitor appears to be kept alive until cancelled, but is this documented?

NWPathMonitor appears to retain itself (or is retained by some internal infrastructure) once it has been started until cancelled. This seems like it can lead to memory leaks if the references to to the monitor are dropped. Is this behavior documented anywhere?

func nwpm_self_retain() {
    weak var weakRef: NWPathMonitor?
    autoreleasepool {
        let monitor: NWPathMonitor = NWPathMonitor()
        weakRef = monitor
        monitor.start(queue: .main)
        // monitor.cancel() // assertion fails unless this is called
    }

    assert(weakRef == nil)
}
nwpm_self_retain()