NoSuchMethodError: DesugarCollections.synchronizedMap in release instrumentation tests with firebase-sessions 3.0.7 (BOM 34.x) #8600

Running Instrumentation tests with minify enabled release builds after updating to the 34.x from 33.x results into a NoSuchMethodError crash as soon as we launch the app in test environment.

Environment

• Firebase BOM: 34.18.0
• firebase-sessions: 3.0.7
• firebase-crashlytics: 20.1.1
• AGP: 8.13.2
• desugar_jdk_libs: 2.1.5 (latest public)
• testBuildType: release
• minifyEnabled: true

Steps to reproduce:

1. Add firebase-crashlytics (or any lib that pulls in firebase-sessions) with BOM 34.x
2. Set minifyEnabled true in release build type
3. Set testBuildType "release" in android block
4. Set coreLibraryDesugaringEnabled true with desugar_jdk_libs:2.1.5
5. Run adb shell am instrument -w -r .test/androidx.test.runner.AndroidJUnitRunner

Expected: instrumentation test runs
Actual: process crashes immediately during FirebaseInitProvider.onCreate before any test runs -

java.lang.NoSuchMethodError: No static method synchronizedMap(Ljava/util/Map;)Ljava/util/Map;
in class Lj$/util/DesugarCollections; or its super classes
(declaration of 'j$.util.DesugarCollections' appears in <package>.test apk)
    at CrashlyticsRegistrar.<clinit>
    at FirebaseInitProvider.onCreate

firebase-sessions:3.0.7 calls DesugarCollections.synchronizedMap() which was compiled against an internal desugaring library that includes this method. In a normal release build this works because Firebase's bundled DesugarCollections (with synchronizedMap) is the only one present. In release instrumentation tests, the test APK brings its own DesugarCollections from the public desugar_jdk_libs:2.1.5 (which lacks synchronizedMap) and it shadows the main APK's version, causing the crash.

Relevant Code:

Attaching a minimal repro project to reproduce this issue.

firebase-desugar-repro.zip