Historically, we have rarely intentionally thrown a
NullPointerException in the Spring Framework. Instead, we prefer to
throw either an IllegalArgumentException or IllegalStateException
instead of a NullPointerException.
However, changes to the code in recent times have introduced the use of
Objects.requireNonNull(Object) which throws a NullPointerException
without an explicit error message.
The latter ends up providing less context than a NullPointerException
thrown by the JVM (since Java 14) due to actually de-referencing a
null-pointer. See https://openjdk.org/jeps/358.
In light of that, this commit revises our current use of
Objects.requireNonNull(Object) by removing it or replacing it with
Assert.notNull().
However, we still use Objects.requireNonNull(T, String) in a few places
where we are required to throw a NullPointerException in order to
comply with a third-party contract such as Reactive Streams.
Closes gh-32430
Prior to this commit, gh-21783 introduced `ReadOnlyHttpHeaders` to avoid
parsing media types multiple times during the lifetime of an HTTP
exchange: such values are cached and the headers map is made read-only.
This also added a new `HttpHeaders.writableHttpHeaders` method to unwrap
the read-only variant when needed.
It turns out this method sends the wrong signal to the community
because:
* the underlying map might be unmodifiable even if this is not an
instance of ReadOnlyHttpHeaders
* developers were assuming that modifying the collection that backs the
read-only instance would work around the cached values for
Content-Type and Accept headers
This commit adds more documentation to highlight the desired behavior
for cached values by the read-only variant, and deprecates the
`writableHttpHeaders` method as `ReadOnlyHttpHeaders` is package private
and we should not surface that concept anyway.
Instead, this commit unwraps the read-only variant if needed when a new
HttpHeaders instance is created.
Closes gh-32116
This commit adds support for application/yaml in MediaType and leverages
jackson-dataformat-yaml in order to support Yaml in RestTemplate,
RestClient and Spring MVC.
See gh-32345
Also fix a couple of related issues:
- add AsyncRequestNotUsableException to the list of exceptions
that imply response issues.
- handle exceptions from @ExceptionHandler regardless of whether
thrown immediately or via Publisher.
Closes gh-32359
The following adjustments are also made as a result:
- Use int to check if lock is held and unlock is needed, given that
for non-async requests we don't need to obtain a lock.
- Protect access methods getOutputStream and getWriter with the
same locking and state checks.
Closes gh-32340
This commit updates ServletServerHttpResponse.ServletResponseHttpHeaders
in order to use ServletResponse#getContentType instead of
ServletResponse#getHeader.
It allows to have a consistent behavior between Tomcat (which sets only
the former) and Undertow/Jetty (which set both).
Closes gh-32339
ServletResponseHttpHeaders#get should be annotated with `@Nullable` and
return null instead of a singleton list containing null when there is no
content type header.
Closes gh-32362
In addition to using the ServletOutputStream, it's also possible to call
ServletResponse#flushBuffer, so the ServletOutputStream wrapper logic needs
to apply there as well.
See gh-32340
The wrapped response prevents use after AsyncListener onError or completion
to ensure compliance with Servlet Spec 2.3.3.4.
The wrapped response is applied in RequestMappingHandlerAdapter.
The wrapped response raises AsyncRequestNotUsableException that is now
handled in DefaultHandlerExceptionResolver.
See gh-32340
This commit refines WebMVC and WebFlux argument resolution in order to
convert properly Kotlin value class arguments by using the type of the
value instead of the type of the value class.
Closes gh-32353
