Decides whether a connection can be kept open after a request.
If this method returns false, the caller MUST
close the connection to correctly comply with the HTTP protocol.
If it returns true, the caller SHOULD attempt to
keep the connection open for reuse with another request.
One can use the HTTP context to retrieve additional objects that
may be relevant for the keep-alive strategy: the actual HTTP
connection, the original HTTP request, target host if known,
number of times the connection has been reused already and so on.
If the connection is already closed, false is returned.
The stale connection check MUST NOT be triggered by a
connection reuse strategy.