fix otlp/json exporter

[lalitb]

#1763

Changes

As discussed here, the unit-test are contributed by @hwrdtm

Please provide a brief description of the changes here.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[lalitb]

Moving to draft to add changelog and enable integration test.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.6%. Comparing base (da368d4) to head (5f93ef3).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1882     +/-   ##
=======================================
- Coverage   74.6%   74.6%   -0.1%     
=======================================
  Files        122     122             
  Lines      19952   19952             
=======================================
- Hits       14902   14901      -1     
- Misses      5050    5051      +1     

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[lalitb]

Moving to draft to add changelog and enable integration test.

ok, I will create a separate PR for adding this to the integration test, it's a slightly bigger effort. We already have the unit test to validate the fix. Also added the changelog.

[lalitb]

merging, will incorporate any new comments in a separate PR.