CreateImageEdit Throw Exception if Mask is null

[hanialaraj]

Describe the bug
When calling CreateImageEdit method, and passing ImageEditCreateRequest object to the method, if the optional parameter "Mask" is not set, it throws an exception
Value cannot be null. (Parameter 'content')|System.ArgumentNullException: Value cannot be null. (Parameter 'content') at System.Net.Http.ByteArrayContent..ctor(Byte[] content) at OpenAI.GPT3.Managers.OpenAIService.CreateImageEdit(ImageEditCreateRequest imageEditCreateRequest)

Your code piece

var imageCreateResponse = await _openAIService.Image.CreateImageEdit(new ImageEditCreateRequest()
{
    Size = "512x512",
    N = 1,
    ImageName = "123456",
    Image = fileBytes,
    User = Cryptography.SHA1Hash("123456789", true),
    Prompt = "Robot, AI"

});

From the SDK source code, there is no check on Mask property before adding it to the request

multipartContent.Add(new ByteArrayContent(imageEditCreateRequest.Mask), "mask", imageEditCreateRequest.MaskName);

public async Task<ImageCreateResponse> CreateImageEdit(ImageEditCreateRequest imageEditCreateRequest)
    {
        var multipartContent = new MultipartFormDataContent();
        if (imageEditCreateRequest.User != null) multipartContent.Add(new StringContent(imageEditCreateRequest.User), "user");
        if (imageEditCreateRequest.ResponseFormat != null) multipartContent.Add(new StringContent(imageEditCreateRequest.ResponseFormat), "response_format");
        if (imageEditCreateRequest.Size != null) multipartContent.Add(new StringContent(imageEditCreateRequest.Size), "size");
        if (imageEditCreateRequest.N != null) multipartContent.Add(new StringContent(imageEditCreateRequest.N.ToString()!), "n");

        multipartContent.Add(new StringContent(imageEditCreateRequest.Prompt), "prompt");
        multipartContent.Add(new ByteArrayContent(imageEditCreateRequest.Image), "image", imageEditCreateRequest.ImageName);
        multipartContent.Add(new ByteArrayContent(imageEditCreateRequest.Mask), "mask", imageEditCreateRequest.MaskName);

        return await _httpClient.PostFileAndReadAsAsync<ImageCreateResponse>(_endpointProvider.ImageEditCreate(), multipartContent);
    }