Migrate debugger-integration-tests cross-project test source sharing to java-test-fixtures for Gradle 9.5 compatibility

[bric3]

What Does This Do

Follow-up to #11367. Replaces the remaining project(':foo').sourceSets.test.output pattern that breaks under Gradle 9.5:

dd-smoke-tests/debugger-integration-tests/build.gradle:21 used:

testImplementation project(':dd-java-agent:agent-debugger').sourceSets.test.output

to pull two helper classes (LogProbeTestHelper, MoshiSnapshotTestHelper) from agent-debugger's test sources. Since the goal was to share test helpers with other projects, this fits the java-test-fixtures plugin: this PR migrates agent-debugger to that plugin, moves the two helpers from src/test/java/com/datadog/debugger/util/ to src/testFixtures/java/com/datadog/debugger/util/ (same package), and switches the consumer to testImplementation testFixtures(project(':dd-java-agent:agent-debugger')).

The 15 existing in-project consumers (test classes inside agent-debugger) keep working because the testFixtures source set is automatically added to the test source set's compile/runtime classpath.

A second commit removes the now-orphaned //testImplementation project(':dd-java-agent:instrumentation:mongo').sourceSets.test.output comment in mongo-common/build.gradle — it was left behind in #11367 as a marker for the broken pattern, but the migration is complete and the comment no longer serves any purpose.

Motivation

Prior to Gradle 9.5, project(':foo') in a dependencies {} block resolved to the real Project object, which gave access to the sourceSets property via Groovy magic.

However, Gradle 9.5 added a DependencyHandler.project(String) returning a ProjectDependency. In Groovy DSL closures this shadows Project.project(String), which was previously resolved as a "fallback" (since DependencyHandler had no project(String) overload before 9.5).

The actual instance returned is now a DefaultProjectDependency instead, which has no sourceSets properties, making the build fail with:

> Could not get unknown property 'sourceSets' for project '...' of type DefaultProjectDependency

Additional Notes

Follow-up to #11367, #10402, #11272.

Contributor Checklist

• Format the title according to the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any other useful labels
• Update the CODEOWNERS file on source file addition, migration, or deletion

🤖 Generated with Claude Code

[pr-commenter]

Debugger benchmarks

Parameters

	Baseline	Candidate
baseline_or_candidate	baseline	candidate
ci_job_date	1779197309	1779197658
end_time	2026-05-19T13:30:00	2026-05-19T13:35:49
git_branch	master	bdu/gradle9-debugger-test-fixtures
git_commit_sha	198a35d	8ea5efc
start_time	2026-05-19T13:28:30	2026-05-19T13:34:19

See matching parameters

	Baseline	Candidate
ci_job_id	1694542191	1694542191
ci_pipeline_id	113956760	113956760
cpu_model	Intel(R) Xeon(R) Platinum 8175M CPU @ 2.50GHz	Intel(R) Xeon(R) Platinum 8175M CPU @ 2.50GHz
git_commit_date	1779196514	1779196514

Summary

Found 0 performance improvements and 0 performance regressions! Performance is the same for 9 metrics, 6 unstable metrics.

See unchanged results

scenario	Δ mean agg_http_req_duration_min	Δ mean agg_http_req_duration_p50	Δ mean agg_http_req_duration_p75	Δ mean agg_http_req_duration_p99	Δ mean throughput
scenario:noprobe	unstable [-27.315µs; +22.445µs] or [-8.711%; +7.158%]	unstable [-39.099µs; +31.676µs] or [-10.839%; +8.782%]	unstable [-54.035µs; +42.478µs] or [-14.239%; +11.194%]	unstable [-142.769µs; +81.626µs] or [-11.234%; +6.423%]	same
scenario:basic	same	same	same	unstable [-120.967µs; +32.294µs] or [-10.713%; +2.860%]	unstable [-136.120op/s; +136.120op/s] or [-5.717%; +5.717%]
scenario:loop	same	same	same	same	same

Request duration reports for reports

gantt
title reports - request duration [CI 0.99] : candidate=None, baseline=None
dateFormat X
axisFormat %s
section baseline
noprobe (360.712 µs) : 323, 398
. : milestone, 361,
basic (311.633 µs) : 304, 319
. : milestone, 312,
loop (9.005 ms) : 8998, 9012
. : milestone, 9005,
section candidate
noprobe (357.001 µs) : 328, 386
. : milestone, 357,
basic (309.922 µs) : 303, 317
. : milestone, 310,
loop (9.011 ms) : 9004, 9018
. : milestone, 9011,

Loading

• baseline results

Scenario	Request median duration [CI 0.99]
noprobe	360.712 µs [323.024 µs, 398.4 µs]
basic	311.633 µs [304.009 µs, 319.256 µs]
loop	9.005 ms [8.998 ms, 9.012 ms]

• candidate results

Scenario	Request median duration [CI 0.99]
noprobe	357.001 µs [328.067 µs, 385.935 µs]
basic	309.922 µs [302.688 µs, 317.156 µs]
loop	9.011 ms [9.004 ms, 9.018 ms]

[dd-octo-sts]

/merge

[gh-worker-devflow-routing-ef8351]

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2026-05-19 17:03:51 UTC ℹ️ Start processing command /merge

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2026-05-19 17:03:56 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 1h (p90).

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2026-05-19 18:26:07 UTC ℹ️ MergeQueue: This merge request was merged