Is there an easy way to go from Instant to XMLGregorianCalendar in Kotlin?

Something like this:

fun DatatypeFactory.newXMLGregorianCalendar(
    instant: Instant,
    zoneId: ZoneId = ZoneId.systemDefault()
): XMLGregorianCalendar {
    return newXMLGregorianCalendar(GregorianCalendar.from(instant.atZone(zoneId)))
}

Some bikeshedding: I'd replace the

{
    return newXML...
}

in your solution with

= this.newXML...

@Sam it's not a Java question at all?

The classes and methods here are all Java, but Kotlin does do a lot to make it more convenient and less verbose 👍