ref(android): Update targetSdk to API 36 (Android 16)

[markushi]

📜 Description

Updates targetSdk and compileSdk to API Level 36 to support Android 16.

This PR addresses breaking changes introduced in Android 16:

• Created ThreadUtil helper class for version-aware thread ID retrieval
• Migrated from deprecated Thread.getId() to Thread.threadId() with backward compatibility for minSdk 21
• Updated sample app to use OnBackPressedCallback instead of deprecated onBackPressed() which is no longer called in Android 16
• Suppressed deprecation warning for onLowMemory() (deprecated in Android 15)

💡 Motivation and Context

Android 16 (API Level 36) deprecates several APIs that the SDK currently uses:

• Thread.getId() is deprecated in favor of Thread.threadId() (available since API 34)
• onBackPressed() is no longer called for apps targeting Android 16

The scheduleAtFixedRate behavior change (only executing ONE missed task instead of ALL) is acceptable and even beneficial for our performance collection use case.

💚 How did you test it?

• Built successfully with ./gradlew spotlessApply apiDump
• All existing tests pass
• Verified backward compatibility with version checks

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

• Add to CHANGELOG.md in # Unreleased section
• Test on Android 16 devices when available

[linear]

ANDROID-16 Persist user information across app launches

[markushi]

@sentry review

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	325.56 ms	398.69 ms	73.13 ms
Size	1.58 MiB	2.20 MiB	633.90 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
abfcc92	337.38 ms	427.39 ms	90.00 ms
d5a29b6	298.62 ms	391.78 ms	93.16 ms
ee747ae	396.82 ms	441.67 ms	44.86 ms
d15471f	294.13 ms	399.49 ms	105.36 ms
91bb874	314.47 ms	440.00 ms	125.53 ms
d15471f	307.28 ms	381.85 ms	74.57 ms
9fbb112	401.87 ms	515.87 ms	114.00 ms
ee747ae	400.46 ms	423.61 ms	23.15 ms
abfcc92	304.04 ms	370.33 ms	66.29 ms
fc5ccaf	256.80 ms	322.36 ms	65.56 ms

App size

Revision	Plain	With Sentry	Diff
abfcc92	1.58 MiB	2.13 MiB	557.31 KiB
d5a29b6	1.58 MiB	2.12 MiB	549.37 KiB
ee747ae	1.58 MiB	2.10 MiB	530.95 KiB
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
91bb874	1.58 MiB	2.13 MiB	559.07 KiB
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
9fbb112	1.58 MiB	2.11 MiB	539.18 KiB
ee747ae	1.58 MiB	2.10 MiB	530.95 KiB
abfcc92	1.58 MiB	2.13 MiB	557.31 KiB
fc5ccaf	1.58 MiB	2.13 MiB	557.54 KiB

Previous results on branch: ref/android-16-target-sdk

Startup times

Revision	Plain	With Sentry	Diff
b51aac3	315.45 ms	345.79 ms	30.34 ms

App size

Revision	Plain	With Sentry	Diff
b51aac3	1.58 MiB	2.20 MiB	633.90 KiB

[markushi]

Retriggered the failed CI checks. The failures appear to be pre-existing flaky tests:

1. SentryTest > if there is work enqueued, init finalizes previous session after that work is done - Flaky test unrelated to Android 16 changes
2. corruptEnvelope UI test on API 34/35 - Element not found issue that also occurs on main branch

These failures are not related to the Android 16 targetSdk update changes in this PR.

[markushi]

Let's move this into AndroidThreadChecker.java

[markushi]

Let's keep this simple.

Suggested change

	- Update Android targetSdk to API 36 (Android 16) ([#5016](https://github.com/getsentry/sentry-java/pull/5016))
	- Migrated from deprecated `Thread.getId()` to `Thread.threadId()` with backward compatibility
	- Created `ThreadUtil` helper for version-aware thread ID retrieval
	- Updated sample app to use `OnBackPressedCallback` instead of deprecated `onBackPressed()`
	- Update Android targetSdk to API 36 (Android 16) ([#5016](https://github.com/getsentry/sentry-java/pull/5016))

[markushi]

Addressed PR feedback:

• Moved getThreadId() from ThreadUtil into AndroidThreadChecker
• Deleted ThreadUtil.java
• Simplified CHANGELOG entry to single line

All changes have been pushed in commit 4a54919.