Issue #5247 ForwardedRequestCustomizer authority order rework

[joakime]

This is an alternate approach for handling the search order for request.authority in ForwardedRequestCustomizer.
With javadoc.

[joakime]

This is the search order for request.authority in an incoming request now.
(this same table is in the javadoc for ForwardedRequestCustomizer in this PR)

num	Value Origin	Host	Port	Notes
1	Forwarded Header	Required	Authoritative	From left-most host=[value] parameter (see rfc7239)
2	X-Forwarded-Host Header	Required	Optional	left-most value
3	X-Forwarded-Port Header	n/a	Required	left-most value (only if getForwardedPortAsAuthority() is true)
4	X-Forwarded-Server Header	Required	Optional	left-most value
5	Request Metadata	Optional	Optional	found in Request Line absolute path and/or Host client request header value as value host:port or host
6	X-Forwarded-Proto Header	n/a	standard	left-most value as http (implied port 80) or https (implied port 443)
7	X-Proxied-Https Header	n/a	boolean	left-most value as on (implied port 443) or off (implied port 80)

[joakime]

Current javadoc says (it looks better formatted, and linked, in javadoc) ...

num	Value Origin	Host	Port	Protocol	Notes
1	Forwarded Header	"host=<host>" param (Required)	"host=<host>:<port>" param (Implied)	"proto=<value>" param (Optional)	From left-most relevant parameter (see rfc7239)
2	X-Forwarded-Host Header	Required	Implied	n/a	left-most value
3	X-Forwarded-Port Header	n/a	Required	n/a	left-most value (only if getForwardedPortAsAuthority() is true)
4	X-Forwarded-Server Header	Required	Optional	n/a	left-most value
5	X-Forwarded-Proto Header	n/a	Implied from value	Required	left-most value becomes protocol.Value of "http" means port=80.Value of "HttpConfiguration.getSecureScheme()" means port=HttpConfiguration.getSecurePort().
6	X-Proxied-Https Header	n/a	Implied from value	boolean	left-most value determines protocol and port.Value of "on" means port=HttpConfiguration.getSecurePort(), and protocol=HttpConfiguration.getSecureScheme()).Value of "off" means port=80, and protocol=http.

[joakime]

@gregw bump. review please.

[gregw]

A couple of niggles, but otherwise LGTM.
I don't think the CI failure is related?

[gregw]

Rather than "Priority" I think "Source" is a better name for this. Will make more sense in logging to see something like "source=XFORWARDED_FOR". It also matches a lot of our webapp config stuff where we record the source, which is then used to determine the priority.

[gregw]

maybe:

Suggested change

	getAuthority().setHost(hostField.getHost(), Priority.FORWARDED);
	getAuthority().setPort(hostField.getPort(), Priority.FORWARDED);
	getAuthority().setHostPort(hostField.getHost(), hostField.getPort(), Priority.FORWARDED);