Migrate tests to JUnit5

Use the following command to find all tests that are still using JUnit4.

grep -rlE "org.junit.[A-Z]" . --include '*.java'

Use the following command to find all tests that are still using JUnit3 components.

grep -rl "junit.framework" . --include '*.java'

Script for the class substitution:

sed -i $1 \
	-e 's/org.junit.After;/org.junit.jupiter.api.AfterEach;/' \
	-e 's/@After$/@AfterEach/' \
	-e 's/org.junit.AfterClass;/org.junit.jupiter.api.AfterAll;/' \
	-e 's/@AfterClass$/@AfterAll/' \
	-e 's/org.junit.Before;/org.junit.jupiter.api.BeforeEach;/' \
	-e 's/@Before$/@BeforeEach/' \
	-e 's/org.junit.BeforeClass;/org.junit.jupiter.api.BeforeAll;/' \
	-e 's/@BeforeClass$/@BeforeAll/' \
	-e 's/org.junit.Test/org.junit.jupiter.api.Test/' \
	-e 's/org.junit.Assert/org.junit.jupiter.api.Assertions/' \
	-e 's/junit.framework.TestCase/org.junit.jupiter.api.Assertions/' \
	-e 's/Assert\./Assertions./'

Notes for converting assertions:

• The order of parameters for assertions with message changed, old: assertEquals(message, expected, actual), new: assertEquals(expected, actual, message). This may result in compile errors that need to be fixed. Also, assertEquals(String, String, String) would successfully compile, but fail during test.
• The name Assertions is a bit longer and conversion might result in lines over 80 chars, causing checkstyle failure.

See also: https://junit.org/junit5/docs/current/user-guide/#migrating-from-junit4

Subtasks that remove the last JUnit4 usage in the submodule should add <allow.junit4>false</allow.junit4> to pom.xml, to prevent new JUnit4 tests being added in the future.