I'm trying to make sense of the following error me...

# getting-started

[CLOVIS]

I'm trying to make sense of the following error message:

Kotlin: Argument type mismatch: actual type is 'Select<CapturedType(out Record!)#1>', but 'Select<out CapturedType(out Record!)#2!>!' was expected.

This is triggered by the code:

val a: Select<out Record?> = TODO()
val b: Select<out Record?> = TODO()
a.unionAll(b)

where Select is declared in Java:

public interface Select<R extends Record>
extends
    ResultQuery<R>,
    TableLike<R>,
    FieldLike,
    FieldOrRowOrSelect
{

    @NotNull @CheckReturnValue
    @Support
    Select<R> unionAll(Select<? extends R> select);

}

Shouldn't <? extends R> allow R itself?