convertOutermostDimension
internal fun convertOutermostDimension(source: PgArray, elementType: KType, sourceType: PgType, context: DeserializationContext): ArrayList<Any?>
The outermost dimension of source, each entry converted to elementType, as an ArrayList.
With one dimension the entries are the elements themselves. With more, each entry is the sub-array one dimension down, handed back to context like any other value - so what it becomes is decided by elementType, one level at a time, by whichever converter claims that type.