How to assign the data from asynchronous (async) service in Syncfusion ASP.NET ReportViewer?

    public class ReportApiController : ApiController,IReportController
    { 
        public object PostReportAction(Dictionary<string, object> jsonResult)
        {
            return ReportHelper.ProcessReport(jsonResult, this);
        }
 
        //Get action for getting resources from the report
        [System.Web.Http.ActionName("GetResource")]
        [AcceptVerbs("GET")]
        public object GetResource(string key, string resourcetype, bool isPrint) 
        {
            return ReportHelper.GetResource(key, resourcetype, isPrint);
        }
        
        //Method will be called when initialize the report options before start processing the report        
        public void OnInitReportOptions(ReportViewerOptions reportOption)
        {            
        }
 
        //Method will be called when reported is loaded
   public async void OnReportLoaded(ReportViewerOptions reportOption)
    {
            if (reportOption.ReportModel.ProcessingMode == ProcessingMode.Local)
            {
                reportOption.ReportModel.DataSources.Clear();
                var ReportData = await GetListAsyncData();
                reportOption.ReportModel.DataSources.Add(new ReportDataSource { Name = "StoreSales", Value = ReportData });
            }
    }
 
   private async Task<IEnumerable<StoreSales>> GetListAsyncData()
   {    
        List<StoreSales> sales = new List<StoreSales>();
        StoreSales strSal = null;
        strSal = new StoreSales()
        {
            SalesOrderID = 43659,
            TotalDue = 23153.2339,
            CustomerID = 29825,
            StateProvinceCode = "GA",
            Store = "Better Bike Shop"
        };
        sales.Add(strSal);
        strSal = new StoreSales()
        {
            SalesOrderID = 43663,
            TotalDue = 472.3108,
            CustomerID = 29565,
            StateProvinceCode = "CA",
            Store = "World Bike Discount Store"
        };
        sales.Add(strSal);
        strSal = new StoreSales()
        {
            SalesOrderID = 43673,
            TotalDue = 4216.0258,
            CustomerID = 29844,
            StateProvinceCode = "NH",
            Store = "Seventh Bike Store"
        };
        sales.Add(strSal);
        strSal = new StoreSales()
        {
            SalesOrderID = 43675,
            TotalDue = 6434.0848,
            CustomerID = 29827,
            StateProvinceCode = "MO",
            Store = "First Bike Store"
        };
        sales.Add(strSal); 
        return sales;
    }
}
 
public class StoreSales
{
    public int SalesOrderID { get; set; }
    public double TotalDue { get; set; }
    public int CustomerID { get; set; }
    public string Store { get; set; }
    public string StateProvinceCode { get; set; }
}