Including nil HTTP header

I am trying to connect to a web service with an HTTP request, and I am
working around with the HTTP headers. I am able to create my own custom
headers for the HTTP request, and everything is fine when the header has
a non-nil value associated to it. However, when I try to set a nil
value to a custom HTTP header, I do not the header included in the HTTP
message. Is there a way to include a header with a nil value in the
HTTP message? Thanks!

Just out of the top of my head: what about setting the header entry to
an empty string value ("")?