Upgrade JUnit4 to JUnit5

[pacphi]

In order to complete this upgrade, I followed public documentation, here:

https://docs.openrewrite.org/running-recipes/popular-recipe-guides/migrate-from-junit-4-to-junit-5

I employed OpenRewrite to perform initial bulk operation with:

mvn -U org.openrewrite.maven:rewrite-maven-plugin:run \
  -Drewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-spring:5.1.7 \
  -Drewrite.activeRecipes=org.openrewrite.java.spring.boot2.SpringBoot2JUnit4to5Migration

I also upgraded dependencies and plugins in root pom.xml:

• Jackson to 2.16.1
• JUnit Jupiter to 5.10.1
• Maven Compiler to 3.12.1
• Maven Surefire to 3.2.3

Afterwards:

• I adjusted imports on AbstractRestTest.java, then replaced a reference to org.junit.ComparisonFailure (no longer available in JUnit5) which was itself is a subclass of java.lang.AssertionError.
• I had to update DefaultApplicationsTest.java, DefaultSpacesTest.java where Supplier<T> anonymous impl for get() method did not have correct visibility.

Result:

• Tests pass for Java 8 and Java 11
  • Maven profile is activated for a installed JDK version detected
  • Defaults to Spring Boot to 2.7.17
  • See https://github.com/pacphi/cf-java-client/actions/runs/7371626056
• Tests fail for Java 17 and 21
  • Maven profile is activated for a installed JDK version detected
  • Sets version of Spring Boot dependencies to 3.2.1
  • See https://github.com/pacphi/cf-java-client/actions/runs/7371626055
  • Observe the following issue targeting Java 17+, here Code generation fails with Java 17 immutables/immutables#1339