Use try-with-resources where possible

[basil]

Before Java 9, we could only use fresh variables inside a try-with-resources block. As of Java 9 and as part of JEP 213, we can now use final or even effectively final variables inside a try-with-resources block. The benefit of try-with-resources is that they suppress exceptions thrown during close, propagating the original exception instead.

Proposed changelog entries

N/A

Proposed upgrade guidelines

N/A

Submitter checklist

• (If applicable) Jira issue is well described
• Changelog entries and upgrade guidelines are appropriate for the audience affected by the change (users or developer, depending on the change) and are in the imperative mood. Examples
  • Fill-in the Proposed changelog entries section only if there are breaking changes or other changes which may require extra steps from users during the upgrade
• Appropriate autotests or explanation to why this change has no tests
• New public classes, fields, and methods are annotated with @Restricted or have @since TODO Javadoc, as appropriate.
• New deprecations are annotated with @Deprecated(since = "TODO") or @Deprecated(forRemoval = true, since = "TODO") if applicable.
• For dependency updates: links to external changelogs and, if possible, full diffs

Desired reviewers

@mention

Maintainer checklist

Before the changes are marked as ready-for-merge:

• There are at least 2 approvals for the pull request and no outstanding requests for change
• Conversations in the pull request are over OR it is explicit that a reviewer does not block the change
• Changelog entries in the PR title and/or Proposed changelog entries are accurate, human-readable, and in the imperative mood
• Proper changelog labels are set so that the changelog can be generated automatically
• If the change needs additional upgrade steps from users, upgrade-guide-needed label is set and there is a Proposed upgrade guidelines section in the PR title. (example)
• If it would make sense to backport the change to LTS, a Jira issue must exist, be a Bug or Improvement, and be labeled as lts-candidate to be considered (see query).

[jtnord]

try-with-resources is null safe.

Why not

        try (InputStream is = CLI.class.getResourceAsStream("/jenkins/cli/jenkins-cli-version.properties")) {
            if (is != null) {
                    props.load(is);
                }
            }

[basil]

Pre-existing issue

[jtnord]

would also seem more readable as:

                try (Archiver a = factory.create(out)) {
                    scanner.scan(f, ignoringSymlinks(a, verificationRoot, noFollowLinks));
                    return a.countEntries();
                }

[basil]

Pre-existing issue

[basil]

I agree that your suggestions are good improvements, but I am not going to fix pre-existing issues not caused by this PR.

[basil]

@jtnord I had some extra time on my day off and the changes seemed relatively simple, so I have accommodated your requests. In the future, kindly refrain from commenting on my PRs with requests for change regarding pre-existing issues.