Force close on connection when 408 is returned

Regarding http1.1 requests.... We have a service we are reaching out to, that is sending back a 408, but no connection: close.  

According to https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/408

The HTTP 408 Request Timeout client error response status code indicates that the server would like to shut down this unused connection. A 408 is sent on an idle connection by some servers, even without any previous request by the client.
A server should send the Connection: close header field in the response, since 408 implies that the server has decided to close the connection rather than continue waiting.

We are using the CloseableHttpAsyncClient with PoolingAsyncClientConnectionManager.  When we get a 408 and they do not specify that connection should be closed, how can we force this? Can it be accomplished with an interceptor or is it done by default inside the library?  The response is actually sending back Connection=keep-alive