Builder options for specifying the default output kinds

[YarnSphere]

On a few projects now, I've been forced to extend DefaultXmlSerializationPolicy just to change the value of defaultPrimitiveOutputKind.

I think it would be a bit nicer to allow users to specify the value of defaultPrimitiveOutputKind and perhaps defaultObjectOutputKind via the builder syntax.

What I write now

val Xml = XML {
    policy = XmlPolicy
}

private object XmlPolicy : DefaultXmlSerializationPolicy({
    encodeDefault = XmlSerializationPolicy.XmlEncodeDefault.NEVER
}) {
    override val defaultPrimitiveOutputKind: OutputKind = OutputKind.Element
}

What I would like to write

val Xml = XML {
    defaultPolicy {
        encodeDefault = XmlSerializationPolicy.XmlEncodeDefault.NEVER
        defaultPrimitiveOutputKind = OutputKind.Element
    }
}

Please let me know if I'm missing something and whether there is already a simpler way of specifying that I want primitives to be encoded as elements by default.