Nullable enums fields are not deserialized

[ievgenii-shepeliuk]

Hello
I have a schema looking like this

{
  "name": "UserInputSubmitted",
  "namespace": "MyNamespace",
  "type": "record",
  "fields": [
    {
      "name": "AccountStatus",
      "type": ["null", {
        "namespace": "MyNamespace",
        "name": "AccountStatus",
        "type": "enum",
        "symbols": ["New","Active"]
      }]
    },
    {
      "name": "IpAddress", "type": "string"
    }
  ]
}

Message are successfully serialized, i.e. published. But when consuming - I get following error

      Chr.Avro.UnsupportedTypeException: A deserializer for a union containing Chr.Avro.Abstract.NullSchema cannot be built for Endeavour.UserInputValidation.Pipelines.Kafka.Abstractions.AccountStatus.
         at Chr.Avro.Serialization.UnionDeserializerBuilderCase.<>c__DisplayClass7_0.<BuildExpression>b__0(Schema child, Int32 index)
         at System.Linq.Enumerable.SelectIterator[TSource,TResult](IEnumerable`1 source, Func`3 selector)+MoveNext()
         at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
         at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
         at Chr.Avro.Serialization.UnionDeserializerBuilderCase.BuildExpression(TypeResolution resolution, Schema schema, IBinaryDeserializerBuilderContext context)
         at Chr.Avro.Serialization.BinaryDeserializerBuilder.BuildExpression(Type type, Schema schema, IBinaryDeserializerBuilderContext context)
         at Chr.Avro.Serialization.RecordDeserializerBuilderCase.<>c__DisplayClass4_3.<BuildExpression>b__7(RecordField field)
         at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()
         at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
         at System.Collections.Generic.SparseArrayBuilder`1.ReserveOrAdd(IEnumerable`1 items)
         at System.Linq.Enumerable.ConcatNIterator`1.LazyToArray()
         at System.Linq.Enumerable.ConcatNIterator`1.ToArray()
         at System.Dynamic.Utils.CollectionExtensions.ToReadOnly[T](IEnumerable`1 enumerable)
         at System.Linq.Expressions.Expression.Block(IEnumerable`1 variables, IEnumerable`1 expressions)
         at Chr.Avro.Serialization.RecordDeserializerBuilderCase.BuildExpression(TypeResolution resolution, Schema schema, IBinaryDeserializerBuilderContext context)
         at Chr.Avro.Serialization.BinaryDeserializerBuilder.BuildExpression(Type type, Schema schema, IBinaryDeserializerBuilderContext context)
         at Chr.Avro.Serialization.BinaryDeserializerBuilder.BuildDelegate[T](Schema schema)
         at Chr.Avro.Confluent.AsyncSchemaRegistryDeserializer`1.<DeserializeAsync>b__16_0(Int32 id)
         at Chr.Avro.Confluent.AsyncSchemaRegistryDeserializer`1.DeserializeAsync(ReadOnlyMemory`1 data, Boolean isNull, SerializationContext context)

Is it expected behaviour or a bug ?

[ievgenii-shepeliuk]

This piece of code is causing the issue UnionDeserializerBuilderCase

I've created my own IBinaryDeserializerBuilderCase overriding UnionDeserializerBuilderCase and removed that block of code.
Now deserialization works.