test: migrate EqualTest to JUnit 5

[MartinWitt]

#3919

Change Log

The following bad smells are refactored:

JUnit4-@test

The JUnit 4 @Test annotation should be replaced with JUnit 5 @Test annotation.

JUnit4Assertion

The JUnit4 assertion should be replaced with JUnit5 Assertions.

The following has changed in the code:

JUnit4-@test

• Replaced junit 4 test annotation with junit 5 test annotation in testEqualsEmptyException
• Replaced junit 4 test annotation with junit 5 test annotation in testEqualsComment
• Replaced junit 4 test annotation with junit 5 test annotation in testEqualsMultitype
• Replaced junit 4 test annotation with junit 5 test annotation in testEqualsActualTypeRef
• Replaced junit 4 test annotation with junit 5 test annotation in testEqualsDetails

JUnit4Assertion

• Transformed junit4 assert to junit 5 assertion in testEqualsEmptyException
• Transformed junit4 assert to junit 5 assertion in testEqualsComment
• Transformed junit4 assert to junit 5 assertion in testEqualsMultitype
• Transformed junit4 assert to junit 5 assertion in testEqualsActualTypeRef
• Transformed junit4 assert to junit 5 assertion in testEqualsDetails

[slarse]

LGTM, thanks @MartinWitt