class Foo { lateinit var i: Integer }
var foo= Foo()

foo.i.isInitialized // =>
// error: unresolved reference. None of the following candidates is applicable because of receiver type mismatch: 
// @SinceKotlin @InlineOnly public val @receiver:AccessibleLateinitPropertyLiteral KProperty0<*>.isInitialized: Boolean defined in kotlin

foo::i.isInitialized // ->error: backing field of 'var i: Integer' is not accessible at this point