Add missing API: HttpResponse.Flush

[Clounea]

Summary

When I try the IHttpModule and HttpApplication in the adapter, I found that HttpResponse.Flush is used in my module(in Sharepoint Online) but it is not supported.

Motivation and goals

HttpResponse.Flush is used in my module(in Sharepoint Online) but it is not supported. I wonder if there is plan to support the API.

In scope

HttpResponse.Flush

Usage example:

Response.StatusCode = 500;
Response.Clear();
Response.Flush();
Response.End();

[joperezr]

@twsouthwick mentioned that he has an implementation for this that has been shared. It will be good to get a confirmation to see if this works as expected.