This first commit for this issue:

- allows JUnit Jupiter to be used for all tests
- adds a dependency on mockito-junit-jupiter
- migrates tests in spring-core to JUnit Jupiter, except parameterized
  tests

The following script was developed in order to semi-automate the
migration process.

https://github.com/sbrannen/junit-converters/blob/master/junit4ToJUnitJupiter.zsh

See gh-23451

ClassLoaderAwareUndeclaredThrowableStrategy fails with a VerifyError on recent JDKs after the CGLIB 3.3 upgrade. The alternative is to replace it with a plain ClassLoaderAwareGeneratorStrategy (extracted from CglibSubclassingInstantiationStrategy) and custom UndeclaredThrowableException handling in CglibMethodInvocation.

See gh-23453

Closes gh-23453

See gh-23451

See gh-23445

Closes gh-23445

Prior to this commit, StopWatch used System.currentTimeMillis() to
track and report running time in milliseconds.

This commit updates the internals of StopWatch to use System.nanoTime()
instead of System.currentTimeMillis(). Consequently, running time is
now tracked and reported in nanoseconds; however, users still have the
option to retrieve running time in milliseconds or seconds.

Closes gh-23235

Closes gh-23391

Since arbitrary levels of proxies do not occur, this commit replaces
the `while` loop in SerializableTypeWrapper.unwrap() with a simple
`if` statement.

Closes gh-23415

Since Java 8, putIfAbsent() is a standard method in java.util.Map. We
therefore no longer need the custom implementation that overrides the
standard implementation in HashMap.

Prior to this commit, AnnotationAttributes#assertNotException checked if
the attribute value was an instance of Exception. Although this was
typically sufficient, the scope was not always broad enough -- for
example, if AnnotationReadingVisitorUtils#convertClassValues stored a
Throwable in the map (such as a LinkageError).

This commit fixes this by checking for an instance of Throwable in
AnnotationAttributes#assertNotException.

Closes gh-23424

Closes gh-23352

Includes consistent use of getContainingClass()

Deprecate all mutation methods in `MethodParameter` in favor of factory
methods that return a new instance. Existing code that previously relied
on mutation has been updated to use the replacement methods.

Closes gh-23385

Prior to this commit, the new `TYPE_HIERARCHY_AND_ENCLOSING_CLASSES`
annotation search strategy failed to find annotations on enclosing
classes if the source class was a nested class that itself had no
annotations present.

This commit fixes this by adding special logic to AnnotationsScanner's
isWithoutHierarchy() method to properly support nested classes.

Closes gh-23378

Add a `TYPE_HIERARCHY_AND_ENCLOSING_CLASSES` annotation search strategy
that can be used to search the full type hierarchy as well as any
enclosing classes.

Closes gh-23378

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

See gh-23378

Update code that's often called so that zero length array results use
a single shared static constant, rather than a new instance for each
call.

Closes gh-23340

See gh-23352

Closes gh-23352

See gh-23382

See gh-23300

Closes gh-23300

This commit upgrades Coroutines support to kotlinx.coroutines
1.3.0-RC, leverages the new Coroutines BOM and refine Coroutines
detection to avoid false positives.

Only Coroutines to Mono context interoperability is supported
for now.

CLoses gh-23326

See gh-23321

Fix `isAssignable` for `ResolvableType.forRawClass` so that it can be
used with types backed by a `TypeVarible`. Prior to this commit the
rawClass value was used, which wouldn't always work.

Closes gh-23321