Issue #11637: Resolve shellcheck SC2016

[ThatSneakyCoder]

Related to #11637.

Doc link: https://www.shellcheck.net/wiki/SC2016

Also important: https://www.shellcheck.net/wiki/SC2154

[ThatSneakyCoder]

@nrmancuso @romani Solving this issue bought new warnings in picture (SC2154). Please check the cli output below:

1. Output before making the necessary changes:

╭─shubh220922@fedora ~/Desktop/checkstyle_project/checkstyle ‹6b77f061b› 
╰─$ shellcheck .ci/*.sh   

In .ci/releasenotes-gen.sh line 55:
              -Dexec.args='${project.version}' \
                          ^------------------^ SC2016 (info): Expressions don't expand in single quotes, use double quotes for that.


In .ci/validation.sh line 12:
    '${base.dir}/../../target/[artifact]-[revision]-all.[ext]' \
    ^-- SC2016 (info): Expressions don't expand in single quotes, use double quotes for that.


In .ci/validation.sh line 773:
                     -Dexec.args='${checkstyle.version}' \
                                 ^---------------------^ SC2016 (info): Expressions don't expand in single quotes, use double quotes for that.

For more information:
  https://www.shellcheck.net/wiki/SC2016 -- Expressions don't expand in singl...

2. Output after making the changes:

╭─shubh220922@fedora ~/Desktop/checkstyle_project/checkstyle ‹sc2016› 
╰─$ shellcheck .ci/*.sh   

In .ci/releasenotes-gen.sh line 55:
              -Dexec.args="${project.version}" \
                           ^----------------^ SC2154 (warning): project is referenced but not assigned.


In .ci/validation.sh line 12:
    "${base.dir}/../../target/[artifact]-[revision]-all.[ext]" \
     ^---------^ SC2154 (warning): base is referenced but not assigned.


In .ci/validation.sh line 773:
                     -Dexec.args="${checkstyle.version}" \
                                  ^-------------------^ SC2154 (warning): checkstyle is referenced but not assigned.

For more information:
  https://www.shellcheck.net/wiki/SC2154 -- base is referenced but not assign...

New type of warning has shown up. We will have to initialize the highlighted properties for this warning to go away as per https://www.shellcheck.net/wiki/SC2016

Edit 1:

@nrmancuso @romani

Can we make use of the uppercase scenario here as in the documentation (https://www.shellcheck.net/wiki/SC2154):

[nrmancuso]

@shubh220922 these look like system/maven properties that we do not want to expand, we can suppress each individually with comment explaining why.

edit: please make comment like we do not want to expand properties in this command

[ThatSneakyCoder]

@nrmancuso Done. Suppressions have been made at respective places. But, what is wrong with making a permanent suppression inshellcheckrc file?

[nrmancuso]

@nrmancuso Done. Suppressions have been made at respective places. But, what is wrong with making a permanent suppression inshellcheckrc file?

While these all look like places that we do not want bash to expand a variable, there is no guarantee about future usages :)

[nrmancuso]

I am good as CI passes

[ThatSneakyCoder]

Fixing CI.

@nrmancuso what kind of an error is this in CI: https://dev.azure.com/romanivanovjr/romanivanovjr/_build/results?buildId=13538&view=logs&j=e663805c-ee13-5a24-f979-d725e0346c8e&t=40ff6e43-c5d7-5753-f947-23012624b0c6&l=929

Potential Solution spotted at https://stackoverflow.com/questions/23260057/the-forked-vm-terminated-without-saying-properly-goodbye-vm-crash-or-system-exi

It seems to be a plugin problem? Still fixing it.

[nrmancuso]

@shubh220922 failure in azure is not related to your changes. The failing job is mvn clean verify ran on MacOS.

[ThatSneakyCoder]

@nrmancuso alright. But wouldn't merging this PR create mvn clean verify issue on MacOS as per the CI.

[nrmancuso]

@shubh220922 it is probably just a random failure, we will have someone with access restart this job before we merge :)