Substitutions in array fail

[sholsapp]

I see an error on lines like this, that contain substitutions. I tried the suggested workaround here, but then the substitutions don't expand as they're interpreted as raw strings.

test.conf

x.y = "foo"
a.b = "baz"

arr = [
          ${x.y}"."${a.b}
]

tool

package main
import (
        "fmt"
        "log"
        "os"
        "github.com/gurkankaymak/hocon"
)
func main() {
        conf, err := hocon.ParseResource(os.Getenv("CONF"))
        if err != nil {
                log.Fatal("error while parsing configuration: ", err)
        }
        fmt.Println(conf)
}

output

2022/12/19 18:46:17 error while parsing configuration: missing comma! at: 5:17, values should have comma or ASCII newline ('\n') between them

Per https://hocon-playground.avelier.dev/ this should work.