UFile (package = ) [public final class MethodReferenceKt {...]
    UClass (name = MethodReferenceKt) [public final class MethodReferenceKt {...}]
        UField (name = x) [private static final var x: kotlin.reflect.KFunction<? extends kotlin.Unit> = Foo::bar]
            UCallableReferenceExpression (name = bar) [Foo::bar] : PsiType:KFunction<? extends Unit>
        UMethod (name = getX) [public static final fun getX() : kotlin.reflect.KFunction<? extends kotlin.Unit> = UastEmptyExpression]
    UClass (name = Foo) [public final class Foo {...}]
        UMethod (name = Foo) [public fun Foo() = UastEmptyExpression]
        UMethod (name = bar) [public final fun bar() : void {...}]
            UBlockExpression [{...}] : PsiType:Unit
