Modernise pom

[timja]

What has been done

1. Modernise pom by updating to newer versions of dependencies and required Jenkins version
   • Jenkins plugins 2.32 -> 4.7
   • Jenkins 2.0 -> 2.204.6
2. Update required Java version 7 -> 8
3. Use https://github.com/jenkinsci/bom to satisfy upper boundary dependencies and no longer manage explicit versions but rather rely on

How to test

1. Make sure project compiles and CI is 🟢
2. Perform the plugin update to new version packaged from current PR to smoke test plotting capabilities after migration to Java 8
3. Make sure Jenkins log doesn't throw any new errors/warnings

Checklist

• Git commits follow best practices
• Build passes in Jenkins
• Appropriate tests or explanation to why this change has no tests
• Pull Request is marked with appropriate label (see .github/release-drafter.yml)
• JIRA issue is well described (problem explanation, steps to reproduce, screenshots)
• For dependency updates: links to external changelogs and, if possible, full diffs

[vgaidarji]

Changes in the PR are good with me 👍
No need to update any classes yet to use Java 8 features.

How does this help with https://issues.jenkins-ci.org/browse/JENKINS-62800? Or it's just the initial project cleanup and the actual fix comes next?

Please provide before/after screenshots for the tables to div fix when ready.

[vgaidarji]

LGTM, please remove the comment above as well.

[vgaidarji]

The build is failing due to Checkstyle warnings. It wasn't the case before and should be caused by upstream changes in buildPlugin()

Those TODO's should probably be removed.

[vgaidarji]

Since buildPlugin() already works with JDK 8 by default, no changes required

[timja]

This was just an initial PR to make testing the plugin easier against the new Jenkins version

[vgaidarji]

@timja thanks for updates here. Will be ok updating the current PR to be focused only on Java 8 migration and adjustments to pom.xml? So that we can merge this PR and it doesn't stay open for long time. And then separate PR to be opened focused only issues.jenkins-ci.org/browse/JENKINS-62800?
If you agree, can you please adjust the PR title/description to match that and we merge it.

[timja]

@timja thanks for updates here. Will be ok updating the current PR to be focused only on Java 8 migration and adjustments to pom.xml? So that we can merge this PR and it doesn't stay open for long time. And then separate PR to be opened focused only issues.jenkins-ci.org/browse/JENKINS-62800?
If you agree, can you please adjust the PR title/description to match that and we merge it.

done

[vgaidarji]

@timja I've updated the PR description and was about to do final testing before merge but CI is not passing and seems like there's some issue with update to 4.7 version of Jenkins plugins performed here #63 (comment).

I have a custom step for code coverage calculation and upload in Jenkinsfile and it fails to find org.jenkins-ci.plugins:plugin:pom:4.7 dependency.

15:49:01  [ERROR]     Non-resolvable parent POM for org.jenkins-ci.plugins:plot:2.1.9-SNAPSHOT: 
Could not find artifact org.jenkins-ci.plugins:plugin:pom:4.7 in central (https://repo.maven.apache.org/maven2) 
and 'parent.relativePath' points at no local POM @ line 4, column 11 -> [Help 2]

[timja]

probably would be easier to just change to buildPlugin? it has code coverage support built in, using code-coverage-api plugin rather than codecov

[codecov]

Codecov Report

Merging #63 (0a45c09) into master (7e38624) will increase coverage by 0.27%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master      #63      +/-   ##
============================================
+ Coverage     43.38%   43.66%   +0.27%     
  Complexity      190      190              
============================================
  Files            18       18              
  Lines          1263     1255       -8     
  Branches        192      192              
============================================
  Hits            548      548              
+ Misses          651      643       -8     
  Partials         64       64              

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/hudson/plugins/plot/Plot.java	26.01% <0.00%> (+0.14%)	30.00 <0.00> (ø)
src/main/java/hudson/plugins/plot/Series.java	81.81% <ø> (ø)	10.00 <0.00> (ø)
...c/main/java/hudson/plugins/plot/SeriesFactory.java	0.00% <0.00%> (ø)	0.00% <0.00%> (ø%)
src/main/java/hudson/plugins/plot/CSVSeries.java	60.89% <0.00%> (+0.38%)	31.00% <0.00%> (ø%)
src/main/java/hudson/plugins/plot/PlotReport.java	46.53% <0.00%> (+0.45%)	10.00% <0.00%> (ø%)
src/main/java/hudson/plugins/plot/XMLSeries.java	72.53% <0.00%> (+0.50%)	36.00% <0.00%> (ø%)
...ain/java/hudson/plugins/plot/PropertiesSeries.java	58.82% <0.00%> (+1.68%)	4.00% <0.00%> (ø%)

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