Revert back to using Stack

[gimantha]

Purpose

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Fixes #

Approach

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Samples

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Remarks

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Check List

• Read the Contributing Guide
• Updated Change Log
• Checked Tooling Support (#)
• Added necessary tests
  • Unit Tests
  • Spec Conformance Tests
  • Integration Tests
  • Ballerina By Example Tests
• Increased Test Coverage
• Added necessary documentation
  • API documentation
  • Module documentation in Module.md files
  • Ballerina By Examples

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.49%. Comparing base (0450329) to head (4f61e6a).
Report is 22 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #43444   +/-   ##
=========================================
  Coverage     77.49%   77.49%           
- Complexity    58594    58596    +2     
=========================================
  Files          3438     3438           
  Lines        219263   219263           
  Branches      28925    28925           
=========================================
+ Hits         169922   169927    +5     
+ Misses        39919    39916    -3     
+ Partials       9422     9420    -2     

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[Shadow-Devil]

Hi @gimantha, I'm curious why this is being reverted. Did something break with this change or was there some performance loss?

[gimantha]

Hi @gimantha, I'm curious why this is being reverted. Did something break with this change or was there some performance loss?

@Shadow-Devil our initial thought was that itemGroup is not concurrently accessed.
It seems like ItemGroup is being accessed concurrently(I cannot confirm though) and intermittently level 2 standard libraries are failing. We will be only reverting that line only. Eventually this class will be remove with Java 21 migration.