union type – complex types (collection []) is accepted but not supported

[mkows]

Currently the below api.json definition is accepted by apibuilder:

  "unions": {
    "item_state": {
      "discriminator": "type",
      "types": [
        { "type": "t1" },
        { "type": "[t2]" }    // <-- NOTE a collection
      ]
    }
  },

where t1, t2 are e.g. enums or models or primitive types.

However, then when Scala code is generated (Play, http4s), it fails with Generator failed with HTTP 500: Unsupported response code[500]. Expected: 200, 409.

Reproduced locally for
https://app.apibuilder.io/michal/playground-api/0.0.3-dev
and the stack trace is

15:12:29.513 [application-akka.actor.default-dispatcher-3] ERROR application - java.lang.RuntimeException: illegal container type List(Enum(Namespaces(io.github.mkows.playground.api.v0),ItemStateFailedCause)) encountered in union [item_state_failed_cause]
java.lang.RuntimeException: illegal container type List(Enum(Namespaces(io.github.mkows.playground.api.v0),ItemStateFailedCause)) encountered in union [item_state_failed_cause]
    at scala.sys.package$.error(package.scala:30)
    at scala.generator.ScalaUnionType$.apply(ScalaService.scala:185)
    at scala.generator.ScalaUnion.$anonfun$types$1(ScalaService.scala:125)
    at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:237)
    at scala.collection.Iterator.foreach(Iterator.scala:941)
    at scala.collection.Iterator.foreach$(Iterator.scala:941)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1429)
    at scala.collection.IterableLike.foreach(IterableLike.scala:74)
    at scala.collection.IterableLike.foreach$(IterableLike.scala:73)
    at scala.collection.AbstractIterable.foreach(Iterable.scala:56)
    at scala.collection.TraversableLike.map(TraversableLike.scala:237)
    at scala.collection.TraversableLike.map$(TraversableLike.scala:230)
    at scala.collection.AbstractTraversable.map(Traversable.scala:108)
    at scala.generator.ScalaUnion.<init>(ScalaService.scala:125)
    at scala.generator.ScalaService.$anonfun$unions$2(ScalaService.scala:36)
    at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:237)

(btw. prev version w/o an array union type works just fine 0.0.2-dev).

Docs:
https://app.apibuilder.io/doc/apiJson#union says for Union Type > type

type specifies the type to include in this union type. Acceptable values include the name of either an enum, a model, or a (primitive type).

So complex type (collection, map) such be rejected (as per current apibuilder docs) when such api.json is uploaded.