It looks like #Java11 decided to completely omit the #contentLength header of an #HttpPost request if the content length equals 0 (zero). That's possible with HTTP/2, but not with HTTP/1.0 or 1.1.

The #RESTAPI server we talk to requires a content-length header even if the payload is empty. Does downgrading to HTTP/1.1 change the behavior of #JavaNetHttp? Does that get the header included?

Or do we have to override default header filtering?