UFile (package = ) [public final class MethodReferenceKt {...]
    UClass (name = MethodReferenceKt) [public final class MethodReferenceKt {...}]
        UField (name = x) [@org.jetbrains.annotations.NotNull private static final var x: kotlin.reflect.KFunction<kotlin.Unit> = Foo::bar]
            UAnnotation (fqName = org.jetbrains.annotations.NotNull) [@org.jetbrains.annotations.NotNull]
            UCallableReferenceExpression (name = bar) [Foo::bar] = external Foo::bar()
        UMethod (name = getX) [public static final fun getX() : kotlin.reflect.KFunction<kotlin.Unit> = UastEmptyExpression]
    UClass (name = Foo) [public final class Foo {...}]
        UMethod (name = bar) [public final fun bar() : void {...}]
            UBlockExpression [{...}] = Undetermined
        UMethod (name = Foo) [public fun Foo() = UastEmptyExpression]
