Fix: SentryTransaction#finish should not clear another transaction from the scope

[maciejwalkowiak]

📜 Description

SentryTransaction#finish should not clear another transaction from the scope

💡 Motivation and Context

Fixes #1269

💚 How did you test it?

📝 Checklist

• I reviewed the submitted code
• I added tests to verify the changes
• I updated the docs if needed
• No breaking changes

[marandaneto]

LGTM
changelog though

[codecov-io]

Codecov Report

Merging #1278 (4360620) into main (e0e8be8) will increase coverage by 0.12%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main    #1278      +/-   ##
============================================
+ Coverage     75.04%   75.16%   +0.12%     
- Complexity     1752     1756       +4     
============================================
  Files           183      183              
  Lines          6159     6161       +2     
  Branches        610      611       +1     
============================================
+ Hits           4622     4631       +9     
+ Misses         1258     1252       -6     
+ Partials        279      278       -1     

Impacted Files	Coverage Δ	Complexity Δ
sentry/src/main/java/io/sentry/Hub.java	75.51% <100.00%> (+0.14%)	76.00 <0.00> (+1.00)
...src/main/java/io/sentry/transport/RateLimiter.java	77.35% <0.00%> (+1.88%)	27.00% <0.00%> (+1.00%)
...n/java/io/sentry/transport/AsyncHttpTransport.java	65.65% <0.00%> (+3.03%)	9.00% <0.00%> (ø%)
...in/java/io/sentry/transport/NoOpEnvelopeCache.java	66.66% <0.00%> (+16.66%)	4.00% <0.00%> (+1.00%)
.../java/io/sentry/transport/CurrentDateProvider.java	100.00% <0.00%> (+33.33%)	3.00% <0.00%> (+1.00%)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e0e8be8...4360620. Read the comment docs.

[bruno-garcia]

On Android where the scope is shared this would race since in between another transaction could have been set.

Another approach would be:

scope.clear(transaction)
And internal conditional atomic reference swap (i.e: https://docs.microsoft.com/en-us/dotnet/api/system.threading.interlocked.compareexchange?view=net-5.0)