/// <summary>
/// Serializes given object into Avro format (including header with metadata)
/// Choosing <paramref name="codecType"/> reduces output object size
/// </summary>
public static byte[] Serialize(object obj, CodecType codecType)
{
    var schema = Schema.Create(obj);

    if (schema is ArraySchema && !obj.GetType().IsDictionary())
    {
        var enumerator = ((IEnumerable)obj).GetEnumerator();

        enumerator.MoveNext();
        var first = enumerator.Current;

        var itemSchema = Schema.Create(first);

        enumerator.Reset();
        using (MemoryStream resultStream = new MemoryStream())
        {
            using (var writer = new Encoder(itemSchema, resultStream, codecType))
            {
                while (enumerator.MoveNext())
                {
                    var item = enumerator.Current;
                    writer.Append(item);
                }
            }

            byte[] result = resultStream.ToArray();
            return result;
        }
    }
    else
    {
        using (MemoryStream resultStream = new MemoryStream())
        {
            using (var writer = new Encoder(schema, resultStream, codecType))
            {
                writer.Append(obj);
            }
            byte[] result = resultStream.ToArray();
            return result;
        }
    }
}

[MemoryDiagnoser]
public class AvroConvertSerializeArray
{
    [Params(100, 1_000, 10_000)]
    public int UserCount;
    private User[] _data;

    [GlobalSetup]
    public void Setup()
    {
        Fixture fixture = new Fixture();
        _data = fixture
            .Build<User>()
            .With(u => u.Offerings, fixture.CreateMany<Offering>(21).ToList)
            .CreateMany(UserCount)
            .ToArray();
    }

    [Benchmark]
    public byte[] Serialize() => AvroConvert.Serialize(_data);

}