Request disable sending Content-Length: 0 on HEAD

[DRSDavidSoft]

I would prefer to do something like this:

if (request->method() == HTTP_HEAD)
{
	response = request->beginResponse(200, "application/octet-stream", "");
	response->setContentLength(0);
	response->setSendContentLength(false); // ?????
	response->addHeader("Content-Length", String(FinalDataSize));
}

Instead, I have to do this:

if (request->method() == HTTP_HEAD)
{
	response = request->beginResponse(200, "application/octet-stream", "");
	response->setContentLength(0);
	response->addHeader("Content-Length", String(FinalDataSize));
}

Which is bad, because it sends the Content-Length twice, once with the incorrect value of 0 and once with the correct Data size. Notice, in the HEAD request we must specify the data's correct Content-Length but MUST NOT send any content whatsover.

If I do response->setContentLength(15); for example, then ESPAsyncWebServer will send 15 bytes of unknown memory to the client which is obviously invalid.

[DRSDavidSoft]

This issue has been solved in mathieucarbou's fork:

• Fix potential duplicate of content-type and content-length mathieucarbou/ESPAsyncWebServer#86
• [Feat] Allow modification of hardcoded headers (Accepts Range, Content-Length) mathieucarbou/ESPAsyncWebServer#77

I'm using that fork now.