C# AnyOf array or string not creating array type

[twodayfbh]

When trying to create an anyOf type I get an object type rather than an array.
The FooResponseObject property is not a List<FooResponseObject> as expected.

Yaml to reproduce:

openapi: 3.0.1
info:
  title: Test API
  version: 1.0.0
paths:
  /foo:
    get:
      responses:
        200:
          description: "OK"
          content:
            application/json:
              schema:
                oneOf:         # <--- create a union type
                - type: string # <--- string |
                - type: array  # <--- FooResponseObject[]
                  items:
                    $ref: "#/components/schemas/FooResponseObject"
components:
  schemas:
    FooResponseObject:
      type: object
      properties:
        id:
          type: string
        name:
          type: string

Output from Kiota:

public class FooGetResponse : IComposedTypeWrapper, IParsable {
    /// <summary>Composed type representation for type FooResponseObject</summary>
#if NETSTANDARD2_1_OR_GREATER || NETCOREAPP3_1_OR_GREATER
#nullable enable
    public HrOn.Client.Foo.FooResponseObject? FooResponseObject { get; set; }
#nullable restore
#else
    public HrOn.Client.Foo.FooResponseObject FooResponseObject { get; set; }
#endif
    /// <summary>Composed type representation for type string</summary>
#if NETSTANDARD2_1_OR_GREATER || NETCOREAPP3_1_OR_GREATER
#nullable enable
    public string? String { get; set; }
#nullable restore
#else
    public string String { get; set; }
#endif
    /// <summary>
    /// Creates a new instance of the appropriate class based on discriminator value
    /// </summary>
    /// <param name="parseNode">The parse node to use to read the discriminator value and create the object</param>
    public static FooGetResponse CreateFromDiscriminatorValue(IParseNode parseNode) {
        _ = parseNode ?? throw new ArgumentNullException(nameof(parseNode));
        var mappingValue = parseNode.GetChildNode("")?.GetStringValue();
        var result = new FooGetResponse();
        if("".Equals(mappingValue, StringComparison.OrdinalIgnoreCase)) {
            result.FooResponseObject = new HrOn.Client.Foo.FooResponseObject();
        }
        else if(parseNode.GetStringValue() is string stringValue) {
            result.String = stringValue;
        }
        return result;
    }
    /// <summary>
    /// The deserialization information for the current model
    /// </summary>
    public virtual IDictionary<string, Action<IParseNode>> GetFieldDeserializers() {
        if(FooResponseObject != null) {
            return FooResponseObject.GetFieldDeserializers();
        }
        return new Dictionary<string, Action<IParseNode>>();
    }
    /// <summary>
    /// Serializes information the current object
    /// </summary>
    /// <param name="writer">Serialization writer to use to serialize this model</param>
    public virtual void Serialize(ISerializationWriter writer) {
        _ = writer ?? throw new ArgumentNullException(nameof(writer));
        if(FooResponseObject != null) {
            writer.WriteObjectValue<HrOn.Client.Foo.FooResponseObject>(null, FooResponseObject);
        }
        else if(String != null) {
            writer.WriteStringValue(null, String);
        }
    }
}

[baywet]

Hi @twodayfbh
Thanks for your interest in kiota and for reporting this.

This is likely caused because the collection kind is not being set here

kiota/src/Kiota.Builder/KiotaBuilder.cs

Line 1721 in f84da5a

TypeDefinition = AddModelDeclarationIfDoesntExist(currentNode, targetSchema, className, shortestNamespace),

You can add a unit test below this one for that specific case

kiota/tests/Kiota.Builder.Tests/KiotaBuilderTests.cs

Line 3428 in f84da5a

public void UnionOfPrimitiveTypesWorks()

With that information in mind, is this something you'd be willing to submit a pull request for?