1. Helper method to eliminate duplication in formatting (de-)serialized
values for logging introduced with prior commit #e62298.
2. Helper method for TRACE vs DEBUG logging with different details.
Issue: SPR-17254
This commit handles "empty" cases for `ResponseEntity` controller
handler return types when wrapped with a `java.util.Optional` in Spring
MVC or a single `Publisher` like `Mono`.
Given the following example for Spring MVC:
```
@GetMapping("/user")
public Optional<ResponseEntity<User>> fetchUser() {
Optional<User> user = //...
return user.map(ResponseEntity::ok);
}
```
If the resulting `Optional` is empty, Spring MVC will infer a
`ResponseEntity` with an empty body and a 404 HTTP response status.
The same reasoning is applied to Spring WebFlux with Publisher types:
```
@GetMapping("/user")
public Mono<ResponseEntity<User>> fetchUser() {
Mono<User> user = //...
return user.map(ResponseEntity::ok);
}
```
This feature is only valid for `HttpEntity` return types and does not
apply to `@ResponseBody` controller handlers.
Issue: SPR-13281
This commit allows to specify a custom CorsConfigurationSource
in AbstractHandlerMapping (both Servlet and Reactive variants).
AbstractHandlerMapping#getCorsConfigurations method is now
deprecated.
Issue: SPR-17067
1. Update ExchangeFilterFunctions to delegate internally to
HttpHeaders.setBasicAuth(user, password).
2. Remove deprecation from
ExchangeFilterFunctions.basicAuthentication(String user, String password)
It is still useful as a filter to insert the header.
3. Update deprecation notes.
Issue: SPR-17099
Forwarded headers are now processed before ServerWebExchange is created
through ForwardedHeaderTransformer which has the same logic as the
ForwardedHeaderFilter but works on the request only.
ForwardedHeaderFilter is deprecated as of 5.1 but if registered it is
removed from the list of filters and ForwardedHeaderTransformer is used
instead.
Issue: SPR-17072
Empty Maps are preferably initialized without capacity (not initializing them at all or lazily initializing with default capacity when needed).
Issue: SPR-17105
This commit introduces Protobuf support in WebFlux via dedicated
codecs.
Flux<Message> are serialized/deserialized using delimited Protobuf
messages with the size of each message specified before the message
itself. In that case, a "delimited=true" parameter is added to the
content type.
Mono<Message> are expected to use regular Protobuf message
format (without the size prepended before the message).
Related HttpMessageReader/Writer are automatically registered when the
"com.google.protobuf:protobuf-java" library is detected in the classpath,
and can be customized easily if needed via CodecConfigurer, for example
to specify protocol extensions via the ExtensionRegistry based
constructors.
Both "application/x-protobuf" and "application/octet-stream" mime types
are supported.
Issue: SPR-15776
Prior to this commit, controller handlers (regular and exception
handlers as well) would not overwrite existing HTTP response headers on
the exchange. This would lead to situations where Content-Type values
set during the initial handling phase would not be overwritten when
handling an error later on.
This commit aligns the implementation of that result handler on the
Spring MVC one in that regard.
Issue: SPR-17082
