Upgrade build to use java 25

[jack-berg]

Update the build to use java 25 (latest LTS) instead of java 21.

There's a strange interaction between java 25 javac, the --release 8 configuration to build java 8 compatible jars, and the guava-beta-checker which makes sure we don't use guava APIs annotated as beta in our source. Its annotation-name lookup triggers java 25 to resolve JSpecify's @NullMarked annotation, including its @Target(MODULE) declaration. Because ElementType.MODULE does not exist in the java 8 API view, javac emits warning: unknown enum constant ElementType.MODULE which causes the build to fail because we set -Werror.

The solution is to:

• Migrate away from guava in published source code
• This allows us to safely remove guava-beta-checker, since we eliminate the chance of accidentally using beta APIs and thus exposing users to errors at runtime when those APIs change
• Add a test to programmatically verify that our published jars don't call guava directly. (Transitive dependencies like grpc may still call guava but then its on them to make sure that they don't leverage beta APIs, and this has always been the case)

[opentelemetry-pr-dashboard]

Pull request dashboard status

Merged · refreshed 2026-10-16 14:00 UTC

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[codecov]

Codecov Report

❌ Patch coverage is 96.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.66%. Comparing base (63150e0) to head (d145420).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ensusshim/OpenTelemetryNoRecordEventsSpanImpl.java	90.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8949      +/-   ##
============================================
+ Coverage     90.61%   90.66%   +0.04%     
- Complexity    10882    10889       +7     
============================================
  Files          1015     1015              
  Lines         29731    29736       +5     
  Branches       3876     3877       +1     
============================================
+ Hits          26942    26959      +17     
+ Misses         1872     1860      -12     
  Partials        917      917              

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