Incorrect default value for a field with ["string","null"] union type and "null" default value

[vkorenev]

For the following Avro schema

{
  "type": "record",
  "name": "Item",
  "fields": [
    { "name": "foo", "type": [ "null", "string" ], "default": null },
    { "name": "bar", "type": [ "string", "null" ], "default": "null" },
    { "name": "baz", "type": [ "string", "null" ], "default": "abcd" }
  ]
}

avrohugger generates the following case class:

final case class Item(
  var foo: Option[String] = None,
  var bar: Option[String] = None,
  var baz: Option[String] = Some("abcd")
) extends org.apache.avro.specific.SpecificRecordBase ...

The default values for foo and baz are correct.
However, the default value for bar should be Some("null"), not None.

[nicodv]

Expected, as the default value of a union corresponds to its first element, see this answer: https://stackoverflow.com/a/23387590/1571826

[vkorenev]

@nicodv, no, this is not expected. The first type of the union for "bar" is string, so the default value should be string as well.

[nicodv]

My bad, was looking at “foo”.