This commit introduces new properties for configuring the HTTP headers
that should be used for forward support.
The new `server.netty.forwarded-headers.header-format` property allows
"standard" or "x_forwarded" to select "Forwarded" or "X-Forwarded-*"
headers.
This aligns the behavior of Netty server with the "FRAMEWORK" strategy.
Closes gh-51031
Refactor `PropertyMapper` so that it no longer calls adapter or
predicate methods by default when the source value is `null`. This
effectively makes all default calls the same as using
`alwaysWhenNotNull` in the previous generation of the code.
For the limited times when you do need to deal with `null` values, the
new `always()` method can be used.
For example,
map.from(source::method).to(destination::method);
Will not call `destination.method(...)` if `source.method()` returns
`null`.
Where as:
map.from(source::method).always().to(destination::method);
Will call `destination.method(null)` if `source.method()` returns
`null`.
This update provides clearer semantics for the API and allows for better
JSpecify nullability annotations. It has also simplified much of our
existing property mapper code.
Closes gh-47024
Co-authored-by: Moritz Halbritter <moritz.halbritter@broadcom.com>
Andy Wilkinson
Manu Sridharan
Brian Clozel
Stéphane Nicoll
Phillip Webb
Daeho Kwon
jdsalasca
Moritz Halbritter