See gh-23451

Closes gh-23476

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

Migrate all existing `assertThat(..., Matcher)` assertions to AssertJ
and add checkstyle rules to ensure they don't return.

See gh-23022

Organize test imports to expand all '.*' static imports into
fully qualified imports.

This update will allow us to use additional checkstyle rules in
the future, and will also help if we migrate fully to AssertJ.

* Add limited checkstyles to test code

Add a limited set of checkstyle rules to the test codebase to improve
code consistency.

* Fix checksyle violations in test code

* Organize imports to fix checkstyle for test code

* Migrate to assertThatExceptionOfType

Migrate aware from ExpectedException rules to AssertJ exception
assertions. Also include a checkstyle rules to ensure that the
the ExpectedException is not accidentally used in the future.

See gh-22894

org.junit.Assert.assertThat() is deprecated as of JUnit 4.13.

See gh-22894

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).

Prior to this commit several test classes named "*Test" were not
recognized as tests by the Gradle build. This is due to the configured
inclusion of '**/*Tests.*' which follows Spring's naming convention for
test classes.

This commit addresses this issue by:

 - Renaming real test classes consistently to "*Tests".
 - Renaming internal test classes to "*TestCase".
 - Renaming @WebTest to @WebTestStereotype.
 - Disabling broken tests in AnnoDrivenStaticEntityMockingControlTest.
 - Modifying the Gradle build configuration so that classes ending in
   either "*Tests" or "*Test" are considered test classes.

Issue: SPR-11384

 - Add TestGroup#LONG_RUNNING to distinguish from #PERFORMANCE, the
   former being tests that simply take a long time vs the latter being
   tests that are actually dependent on certain actions happening within
   a given time window and are thefore CPU-dependent.

Issue: SPR-9984

  find . -type f -name "*.java" -or -name "*.aj" | \
    xargs perl -p -i -e "s/[ \t]*$//g" {} \;

Issue: SPR-10127

This renaming more intuitively expresses the relationship between
subprojects and the JAR artifacts they produce.

Tracking history across these renames is possible, but it requires
use of the --follow flag to `git log`, for example

    $ git log spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history up until the renaming event, where

    $ git log --follow spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history for all changes to the file, before and after the
renaming.

See http://chrisbeams.com/git-diff-across-renamed-directories

Prior to this change, roughly 5% (~300 out of 6000+) of files under the
source tree had CRLF line endings as opposed to the majority which have
LF endings.

This change normalizes these files to LF for consistency going forward.

Command used:

$ git ls-files | xargs file | grep CRLF | cut -d":" -f1 | xargs dos2unix

Issue: SPR-5608

Prior to this change, roughly 5% (~300 out of 6000+) of files under the
source tree had CRLF line endings as opposed to the majority which have
LF endings.

This change normalizes these files to LF for consistency going forward.

Command used:

$ git ls-files | xargs file | grep CRLF | cut -d":" -f1 | xargs dos2unix

Issue: SPR-5608

+ remove class definitions for sticking around (by forcing eager metadata initialization)
+ improve cache size by eliminating the numbers of method metadata objects created
+ improve lookup access on method metadata

+ replace the vanilla hashmap with a quick-and-dirty, JDK based, fixed LRU cache