See gh-19930

See gh-19930

This is a work in progress (WIP) which includes failing tests.

See gh-19930

This commit redeclares default methods in AbstractTestExecutionListener
in order to make them inlinable.

Rename `SearchStrategy.EXHAUSTIVE` from `MergedAnnotations` to
`SearchStrategy.TYPE_HIERARCHY`

See gh-23378

See gh-23320

See gh-23320

Prior to this commit, if multiple, directly present
`@TestPropertySource` annotations declared the same property, the
precedence ordering was top-down instead of bottom-up, in contrast to
the semantics for class hierarchies. In other words, a subsequent
`@TestPropertySource` annotation could not override a property in a
previous `@TestPropertySource` annotation.

This commit overhauls the internals of `TestPropertySourceUtils` in
order to provide proper support for property overrides within local,
directly present `@TestPropertySource` declarations.

Specifically, the `locations` and `properties` attributes from all
`@TestPropertySource` declarations that are directly present or
meta-present on a given class are now merged into a single instance of
`TestPropertySourceAttributes` internally, with assertions in place to
ensure that such "same level" `@TestPropertySource` declarations do not
configure different values for the `inheritLocations` and
`inheritProperties` flags. Effectively, all "same level"
`@TestPropertySource` declarations are treated internally as if there
were only one such annotation declared by the user.

See gh-23320

Prior to this commit, @TestPropertySource could not be declared as a
repeatable annotation. In addition, a local declaration of
@TestPropertySource would silently override a meta-present
@TestPropertySource.

This commit addresses this issue by introducing @TestPropertySources as
a container for @TestPropertySource. This commit also updates the
search and algorithms within TestPropertySourceUtils.

Closes gh-23320

See gh-23224

Prior to this commit, @TestConstructor supported a boolean `autowire`
attribute which naturally limited the configuration to two states: on
or off. Since we may need to support additional autowiring modes in the
future, the use of a boolean is limiting.

This commit address this issue by introducing a new AutowireMode enum
in @TestConstructor with ALL and ANNOTATED constants. In addition, the
attribute has been renamed to `autowireMode`, and the system property
has been renamed to `spring.test.constructor.autowire.mode` for greater
clarity of purpose.

Closes gh-23224

Closes gh-23036

Prior to this commit, dependency injection of all arguments in a test
class constructor invoked by JUnit Jupiter was only possible if the
constructor was explicitly annotated with @Autowired.

This commit introduces support for a configurable "test constructor
autowire" mode which defaults to false in order to remain backwards
compatible.

Specifically, this mode can be configured globally for an entire test
suite via a new "spring.test.constructor.autowire" JVM system property
that can alternatively be configured via the SpringProperties
mechanism. In addition, the global "test constructor autowire" mode can
be overridden locally on a per-class basis via the new @TestConstructor
annotation.

Closes gh-22286

This commit introduces support in the Spring TestContext Framework
(TCF) to query whether the test's ApplicationContext is available.

Specifically, this commit introduces the following two `default`
methods along with corresponding implementations in DefaultTestContext
and DefaultCacheAwareContextLoaderDelegate.

- `boolean hasApplicationContext()` in the TestContext API

- `boolean isContextLoaded(MergedContextConfiguration)` in the
  CacheAwareContextLoaderDelegate API

Closes gh-22756

This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).

# Fixed URLs

## Fixed Success
These URLs were switched to an https URL with a 2xx status. While the status was successful, your review is still recommended.

* [ ] http://www.apache.org/licenses/ with 1 occurrences migrated to:
  https://www.apache.org/licenses/ ([https](https://www.apache.org/licenses/) result 200).
* [ ] http://www.apache.org/licenses/LICENSE-2.0 with 6515 occurrences migrated to:
  https://www.apache.org/licenses/LICENSE-2.0 ([https](https://www.apache.org/licenses/LICENSE-2.0) result 200).

This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).

# Fixed URLs

## Fixed Success
These URLs were switched to an https URL with a 2xx status. While the status was successful, your review is still recommended.

* [ ] http://www.apache.org/licenses/ with 1 occurrences migrated to:
  https://www.apache.org/licenses/ ([https](https://www.apache.org/licenses/) result 200).
* [ ] http://www.apache.org/licenses/LICENSE-2.0 with 6625 occurrences migrated to:
  https://www.apache.org/licenses/LICENSE-2.0 ([https](https://www.apache.org/licenses/LICENSE-2.0) result 200).

Issue: SPR-17137

Reorganize imports to ensure consistent ordering. This commit also
expands any `.*` static imports in favor of using fully-qualified
method references.

Issue: SPR-16968

Ensure that `this.` is used consistently when accessing class
fields.

Issue: SPR-16968

Fix checkstyle violations for javadoc.

Issue: SPR-16968

Includes consistent use of ClassUtils.toClassArray (as non-null variant)

Issue: SPR-16523

Issue: SPR-16369

Issue: SPR-16369

This commit introduces the following changes.

1) It adds a new Spring @NonNull annotation which allows to apply
@NonNullApi semantic on a specific element, like @Nullable does.
Combined with @Nullable, it allows partial null-safety support when
package granularity is too broad.

2) @Nullable and @NonNull can apply to ElementType.TYPE_USE in order
to be used on generic type arguments (SPR-15942).

3) Annotations does not apply to ElementType.TYPE_PARAMETER anymore
since it is not supported yet (applicability for such use case is
controversial and need to be discussed).

4) @NonNullApi does not apply to ElementType.FIELD anymore since in a
lot of use cases (private, protected) it is not part for the public API
+ its usage should remain opt-in. A dedicated @NonNullFields annotation
has been added in order to set fields default to non-nullable.

5) Updated Javadoc and reference documentation.

Issue: SPR-15756

Issue: SPR-15869

Issue: SPR-15720
Issue: SPR-15792

This commits extends nullability declarations to the field level, formalizing the interaction between methods and their underlying fields and therefore avoiding any nullability mismatch.

Issue: SPR-15720

This commit also removes nullability from two common spots: ResolvableType.getType() and TargetSource.getTarget(), both of which are never effectively null with any regular implementation. For such scenarios, a non-null empty type/target is the cleaner contract.

Issue: SPR-15540

Issue: SPR-15540

This commit introduces 2 new @Nullable and @NonNullApi
annotations that leverage JSR 305 (dormant but available via
Findbugs jsr305 dependency and already used by libraries
like OkHttp) meta-annotations to specify explicitly
null-safety of Spring Framework parameters and return values.

In order to avoid adding too much annotations, the
default is set at package level with @NonNullApi and
@Nullable annotations are added when needed at parameter or
return value level. These annotations are intended to be used
on Spring Framework itself but also by other Spring projects.

@Nullable annotations have been introduced based on Javadoc
and search of patterns like "return null;". It is expected that
nullability of Spring Framework API will be polished with
complementary commits.

In practice, this will make the whole Spring Framework API
null-safe for Kotlin projects (when KT-10942 will be fixed)
since Kotlin will be able to leverage these annotations to
know if a parameter or a return value is nullable or not. But
this is also useful for Java developers as well since IntelliJ
IDEA, for example, also understands these annotations to
generate warnings when unsafe nullable usages are detected.

Issue: SPR-15540