Feature java version check again

[halirutan]

OK, I added some comment about the Java 9 check and why we should leave it in for the moment. The rest is unchanged but updated to the latest master.

• Change in CHANGELOG.md described
• Tests created for changes
• Screenshots added (for bigger UI changes)
• Manually tested changed features in running JabRef
• Check documentation status (Issue created for outdated help page at help.jabref.org?)
• If you changed the localization: Did you run gradle localizationUpdate?

[tobiasdiez]

Code looks good to me. But for the next time: please use parametrized tests (for junit5 but I'm not sure we have already updated, there is also something similar for junit4).

[halirutan]

@tobiasdiez I'm not exactly sure how this would have been possible here. For some sub-test sure, but would it have been possible to make nested loops where I test all java8 versions against all java9 version when I provide them as parameter test?

[tobiasdiez]

Yes, I think that is possible. The junit 5 documentation contains the code

@ParameterizedTest
@MethodSource("stringAndIntProvider")
void testWithMultiArgMethodSource(String first, int second) {
    assertNotNull(first);
    assertNotEquals(0, second);
}

static Stream<Arguments> stringAndIntProvider() {
    return Stream.of(Arguments.of("foo", 1), Arguments.of("bar", 2));
}

By changing stringAndIntProvider you can generate every possible combination of java 8 and java 9 version strings. Anyway, no need to change it for this PR. Was just a remark for the next time.

[halirutan]

Can this be merged? If yes, would some of the veterans do this?

[Siedlerchr]

@halirutan If you are ready, add the label "ready for review". From my point of view it's good now.