feat(spring): [Logs and Metrics Enable Flags 15] Warn for legacy Metrics property

[adinauer]

PR Stack (Logs and Metrics Enable Flags)

• feat(core): Remove Logs and Metrics enable flags #5939
• feat(logback): [Logs and Metrics Enable Flags 1] Add Logs opt-in #5940
• feat(log4j2): [Logs and Metrics Enable Flags 2] Add Logs opt-in #5941
• feat(jul): [Logs and Metrics Enable Flags 3] Add Logs opt-in #5942
• feat(android): [Logs and Metrics Enable Flags 4] Add Timber Logs opt-in #5943
• feat(android): [Logs and Metrics Enable Flags 5] Add Logcat Logs opt-in #5945
• feat(spring): [Logs and Metrics Enable Flags 6] Add logging Logs opt-in #5946
• feat(core): [Logs and Metrics Enable Flags 7] Remove Logs enable flag #5947
• feat(android): [Logs and Metrics Enable Flags 8] Warn for legacy Logs metadata #5949
• feat(core): [Logs and Metrics Enable Flags 9] Warn for legacy Logs configuration #5950
• feat(spring): [Logs and Metrics Enable Flags 10] Warn for legacy Logs property #5951
• perf(core): [Logs and Metrics Enable Flags 11] Avoid unused Logs worker thread #5952
• feat(core): [Logs and Metrics Enable Flags 12] Remove Metrics enable flag #5953
• feat(android): [Logs and Metrics Enable Flags 13] Warn for legacy Metrics metadata #5954
• feat(core): [Logs and Metrics Enable Flags 14] Warn for legacy Metrics configuration #5955
• feat(spring): [Logs and Metrics Enable Flags 15] Warn for legacy Metrics property #5956
• perf(core): [Logs and Metrics Enable Flags 16] Avoid unused Metrics worker thread #5957
• fix(jul): [Logs and Metrics Enable Flags 17] Preserve null-message records #5960
• docs: [Logs and Metrics Enable Flags 18] Update options guidance #5961
• fix(android): [Logs and Metrics Enable Flags 19] Read Timber option lazily #5964
• fix(core): [Logs and Metrics Enable Flags 20] Make migration warnings visible #5966

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📜 Description

Detects explicit sentry.metrics.enabled configuration through Spring's Environment in all three Spring Boot variants. Migration warnings are emitted after Sentry.init, when the diagnostic logger has been initialized.

Both true and false values emit tailored migration warnings. The obsolete property is not added back to SentryProperties and does not affect manual Metrics capture. Absent configuration emits no warning.

💡 Motivation and Context

After removal of the aggregate Metrics option, Spring's relaxed binder ignores the old property. Inspecting the complete Spring Environment preserves a useful migration diagnostic across property files, YAML, environment variables, command-line values, and other property sources.

💚 How did you test it?

• ./gradlew :sentry-spring-boot:test :sentry-spring-boot-jakarta:test :sentry-spring-boot-4:test
• ./gradlew spotlessApply apiDump
• Added absent, explicit true, and explicit false tests to all three Spring Boot variants

📝 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

Avoid starting the Metrics batch worker thread until the first accepted Metrics item.

#skip-changelog

⚠️ Merge this PR using a merge commit (not squash). Only the collection branch is squash-merged into main.

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📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

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📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.52.0 (1)	release

⚙️ sentry-android Build Distribution Settings

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Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	320.24 ms	363.04 ms	42.80 ms
Size	0 B	0 B	0 B