RestEasy-Netty4: Connection close header not being returned to the client

When a request is made to a resteasy-netty4 endpoint with the "Connection:close" header, the response does not contain a "Connection:close header". This is causing the request that follows it to try and re-use the closed connection as the client has not closed the connection on its side. The 2nd request in this case fails.

To reproduce:

• Create a jmeter http request sampler with keep alive off
• Send 10 requests from one user (thread)
• Notice that every 2nd request fails

Using wireshark it can be seen that a RST tcp packet is being sent from the server to the client on every second request.

Pull request for a fix is attached.