This commit moves the spring-web dependency from implementation to
optional. It also adds an api dependency to spring-web in the rsocket
starter.
The reasoning behind this change is that RSocket can be used without
spring-web, and we want to make sure that consumers of the dependency
can achieve that goal, as they were able to in previous versions.
However, we believe that most RSocket-based applications need spring-web
as, without it, only the simple and not efficient implementation of
RouterMatcher is available. With the addition of exception handling
using ControllerAdvice, this change makes also sure that it works out
of the box with the starter.
Closes gh-47409
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>