Decorating an IEnumerable request property with JsonRequired causes instantiation of abstract ICollection

[jonmarozick]

Describe the bug

A request class with an IEnumerable property decorated with JsonRequired is assigned a new ICollection which generates a compiler error.

Version of NSwag toolchain, computer and .NET runtime used

Both 14.2.0 and 14.3.0 have this issue. I didn't test prior versions.
C# .NET 8 WebAPI
Windows 10
Visual Studio Version 17.13.6

To Reproduce

public class SaveRequest
{
    [Newtonsoft.Json.JsonRequired]
    public IEnumerable<UserType> UserTypes { get; set; }
}

Generates this:

[System.CodeDom.Compiler.GeneratedCode("NJsonSchema", "14.3.0.0 (NJsonSchema v11.2.0.0 (Newtonsoft.Json v13.0.0.0))")]
public partial class SaveRequest
{
    [Newtonsoft.Json.JsonProperty("userTypes", Required = Newtonsoft.Json.Required.Always, ItemConverterType = typeof(Newtonsoft.Json.Converters.StringEnumConverter))]
    public System.Collections.Generic.ICollection<UserType> UserTypes { get; set; } = new System.Collections.Generic.ICollection<UserType>();
}

Expected behavior

I would expect the generated code to be a concrete class such as a List.

[System.CodeDom.Compiler.GeneratedCode("NJsonSchema", "14.3.0.0 (NJsonSchema v11.2.0.0 (Newtonsoft.Json v13.0.0.0))")]
public partial class SaveRequest
{
    [Newtonsoft.Json.JsonProperty("userTypes", Required = Newtonsoft.Json.Required.Always, ItemConverterType = typeof(Newtonsoft.Json.Converters.StringEnumConverter))]
    public System.Collections.Generic.ICollection<UserType> UserTypes { get; set; } = new System.Collections.Generic.List<UserType>();
}

Additional context

As a work around I removed the JsonRequired attribute and used a validator to ensure the incoming data has at least 1 item in the collection.