Add CI workflow for Java 8

[davidcui1225]

Description

Add CI workflow to test reports-scheduler with Java 8

Issues Resolved

#230

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• [ x] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[dblock]

Did you try building and testing on 8? That would be preferred than building on 11 then testing on 11 unless it's too much work.

[davidcui1225]

Did you try building and testing on 8? That would be preferred than building on 11 then testing on 11 unless it's too much work.

When I build on 8 I get the following error on compileKotlin:

e: /Users/davidcui/dashboards-reports/reports-scheduler/src/main/kotlin/org/opensearch/reportsscheduler/settings/PluginSettings.kt: (98, 46): Unresolved reference: of

That is referencing this line:

val defaultSettingYmlFile = Path.of(configDirName, PLUGIN_NAME, "reports-scheduler.yml")

I can debug but wanted to get a working version posted first

[joshuali925]

@davidcui1225 opensearch-project/OpenSearch#1591 (comment)

[davidcui1225]

@davidcui1225 opensearch-project/OpenSearch#1591 (comment)

From what I'm reading here l don't see an explicit solution for this issue yet? Is the current strategy of building with 11 and testing against 8 an acceptable workaround for the time being then?

[davidcui1225]

@davidcui1225 opensearch-project/OpenSearch#1591 (comment)

From what I'm reading here l don't see an explicit solution for this issue yet? Is the current strategy of building with 11 and testing against 8 an acceptable workaround for the time being then?

@dblock ?

[davidcui1225]

Testing with JDK 8 against integTest has the same issue as building with JDK 8, with NoSuchMethodError on Path.of.

[codecov-commenter]

Codecov Report

Merging #303 (f394574) into main (265e2a7) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main     #303   +/-   ##
=========================================
  Coverage     72.75%   72.75%           
  Complexity      369      369           
=========================================
  Files            94       94           
  Lines          3928     3928           
  Branches        609      609           
=========================================
  Hits           2858     2858           
  Misses          894      894           
  Partials        176      176           

Flag	Coverage Δ
dashboards-reports	77.21% <ø> (ø)
reports-scheduler	68.70% <ø> (ø)

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[davidcui1225]

Closing for #304