build(android): Pin AAR minCompileSdk to minSdk (#5823)

* build(android): Pin AAR minCompileSdk to minSdk

AGP 9 changed the default so a published library's AAR metadata
minCompileSdk mirrors its compileSdk, which we recently bumped to 37.
That would force every consumer of the Android SDK onto compileSdk 37.

Pin minCompileSdk to our minSdk for all published Android library
modules so consumers stay free to compile against any SDK we support,
preserving the pre-AGP-9 behavior.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* changelog

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: runningcode

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Fixes
+
+- Pin the published Sentry Android SDK's AAR metadata `minCompileSdk` to our `minSdk` (`21`) instead of AGP 9's new default of the SDK's own `compileSdk` (`37`), so apps that depend on the SDK aren't forced to raise their `compileSdk` ([#5823](https://github.com/getsentry/sentry-java/pull/5823))
+
 ### Performance
 
 - Reduce the number of SDK threads: `LifecycleWatcher` now schedules the session-end task on the shared timer executor instead of creating a dedicated `java.util.Timer` thread ([#5819](https://github.com/getsentry/sentry-java/pull/5819))

build.gradle.kts

@@ -177,6 +177,13 @@ subprojects {
                     sourceCompatibility = JavaVersion.VERSION_1_8
                     targetCompatibility = JavaVersion.VERSION_1_8
                 }
+
+                // AGP 9 defaults the AAR metadata minCompileSdk to the library's compileSdk,
+                // which would force every consumer onto that compile SDK. Pin it to our minSdk
+                // so consumers remain free to compile against any SDK we support, as before.
+                defaultConfig {
+                    aarMetadata { minCompileSdk = libs.versions.minSdk.get().toInt() }
+                }
             }
         }