TLDR: Is there a way to force OkHttp to correctly handle unexpected/unrequested 100 Continue HTTP responses?
I'm using OkHttp 3.8.1 on Android to POST to a poorly-behaved server.
Even though the request does not include an "Expect: 100-continue" header, the web server returns a 100 Continue response. Rather than continuing to send the request body, then getting the actual (200) response, OkHttp stops there and sends back the 100 Continue response in my okhttp.Callback.
I tried explicitly including "Expect: 100-continue" in the request to trigger OkHttp's logic, but the server (possibly due to some bug) claims the header is malformed and rejects the request. I also tried sending "Expect:" (no value), but the server still sends the 100 Continue response and OkHttp stops there.
Other HTTP clients (I've tested 3 so far) can talk to that server just fine. They handle the 100 Continue response correctly even though they didn't see "Expect: 100-continue" in the request header. Is there an option I can set, or an interceptor I can write, to make OkHttp do the same?