Shallow copying EnvironmentVariables map before injecting ArrayNode env vars

[hamersaw]

Tracking issue

fixes #5171

Why are the changes needed?

In ArrayNode executions where the execution context has environment variables each subNode evaluation will attempt to inject maptask specific variables into the same map. This is because golang passes all maps by reference.

What changes were proposed in this pull request?

In this PR we updated the arrayExecutionContext to shallow copy existing environment variables so each subNode evaluation maintains their own replica before injecting maptask specific environment variables. This ensures that there can not be concurrent map writes in the case of parallelized subNode evaluations.

How was this patch tested?

Printed memory addresses of EnvironmentVariables map before and after change and viewed a change.

Setup process

NA

Screenshots

NA

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

NA

Docs link

NA

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.06%. Comparing base (dc1294e) to head (f8fe4ae).
Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5182      +/-   ##
==========================================
- Coverage   59.11%   59.06%   -0.05%     
==========================================
  Files         645      646       +1     
  Lines       55574    55726     +152     
==========================================
+ Hits        32852    32916      +64     
- Misses      20129    20214      +85     
- Partials     2593     2596       +3     

Flag	Coverage Δ
unittests	59.06% <100.00%> (-0.05%)	⬇️

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