You need double exclamation mark like so:
val bar = makeNewBar(foo.name!!)
As documented in Null Safety section:
The third option is for NPE-lovers. We can write b!!, and this will
return a non-null value of b (e.g., a String in our example) or throw
an NPE if b is null:val l = b!!.lengthThus, if you want an NPE, you can have it, but you have to ask for it explicitly, and it does not appear out of the
blue.