Wrapper that accepts both scalar and collection

Question

Can I somehow refactor this into one class? Some things are common here like Metadata property.

public class Resource<TEntity>
{
    public TEntity Data { get; set; }

    public Dictionary<string, string> Metadata { get; set; }

    public Resource(TEntity data)
    {
        Data = data;
    }
}

public class ResourceCollection<TEntity>
{
    public ICollection<TEntity> Data { get; set; }

    public Dictionary<string, string> Metadata { get; set; }

    public int Count { get; set; }

    public ResourceCollection(ICollection<TEntity> data)
    {
        Data = data;

        Count = data.Count;
    }
}

Is this possible to make interface that expects either ICollection<TEntity> or TEntity alone?

This wrapper class is used for serialization it simply acts as a wrapper, but still I have some doubts about it that it could be done better

I also came up with this:

public class Resource<T>
{
    public T Data { get; set; }

    [JsonExtensionData]
    public Dictionary<string, object> Metadata { get; set; } = new Dictionary<string, object>();

    public Resource(T data)
    {
        Data = data;

        if (data is ICollection collection)
        {
            Metadata["count"] = collection.Count;
        }
    }
}

Answer 1

I guess you could use inheritance if you really need that extra property:

public class ResourceCollection<TEntity> : Resource<ICollection<TEntity>>
{
    public ResourceCollection(ICollection<TEntity> data) : base(data)
    {
        //modify metadata if needed
    }

    public int Count => Data.Count;
}

While technically this is still two classes, you can now cast your collections to Resource<T> and process them in generic manner with your other resources.