Button to create .Zip file from files attached to Acumatica document

ZipArchiveCreateBtn.cs

public PXAction<ARInvoice> CreateZip;

        [PXButton(CommitChanges = false)]
        [PXUIField(DisplayName = "Create .Zip", MapEnableRights = PXCacheRights.Update, MapViewRights = PXCacheRights.Update, Enabled = true)]
        protected virtual IEnumerable createZip(PXAdapter pxAdapter)
        {
            if (Base.Document.Current != null)
            {
                UploadFileMaintenance uploadFileMaint = PXGraph.CreateInstance<UploadFileMaintenance>();

                PX.SM.FileInfo fileInfo;

                using (MemoryStream zipStream = new MemoryStream())
                {
                    using(ZipArchive zipArchive = ZipArchive.CreateFrom(zipStream, false))
                    {
                        //Retrieves files from the invoice
                        foreach (Guid file in PXNoteAttribute.GetFileNotes(Base.Document.Cache, Base.Document.Current))
                        {
                            fileInfo = uploadFileMaint.GetFile(file);

                            if(fileInfo != null)
                            {
                                zipArchive.AddFile(fileInfo.Name, fileInfo.BinData);
                            }
                        }
                    }

                    //Create Acumatica file from .Zip file content
                    fileInfo = new PX.SM.FileInfo("Test.Zip", null, zipStream.ToArray());

                    //Saves file to Invoice
                    if (uploadFileMaint.SaveFile(fileInfo, FileExistsAction.CreateVersion))
                    {
                        PXNoteAttribute.AttachFile(Base.Document.Cache, Base.Document.Current, fileInfo);
                    }
                }
            }
            return pxAdapter.Get();
        }