PR Stack (SDK Overhead Reduction)

• perf(core): SDK Overhead Reduction #5499
• perf(core): [SDK Overhead Reduction 1] Skip java.specification.version lookup on Android #5500
• perf(android): [SDK Overhead Reduction 2] Replace reflective OptionsContainer with direct subclass #5501
• perf(android): [SDK Overhead Reduction 3] Reuse SentryExecutorService for DeviceInfoUtil pre-caching #5502
• perf(android): [SDK Overhead Reduction 4] Use default timezone directly #5587
• perf(core): [SDK Overhead Reduction 5] Replace Calendar with Date in DateUtils #5589
• perf(core): [SDK Overhead Reduction 6] Reduce JsonWriter stack allocation #5591
• perf(core): [SDK Overhead Reduction 7] Lazily allocate Breadcrumb data #5598
• perf(core): [SDK Overhead Reduction 8] Reduce context serialization allocations #5599
• perf(core): [SDK Overhead Reduction 9] Lazily allocate reflection serializer state #5600
• perf(core): [SDK Overhead Reduction 10] Lazily create reflection JSON serializer #5601
• perf(core): [SDK Overhead Reduction 11] Replace ISO8601 timestamp handling #5602
• perf(core): [SDK Overhead Reduction 12] Avoid cloning Date getters #5603
• fix(core): [SDK Overhead Reduction 13] Preserve ISO8601 utility compatibility #5609

📜 Description

Avoid cloning mutable Date values from SDK data model getters. These getters now return the stored Date reference directly, matching the broader SDK behavior of exposing mutable model data through getters.

💡 Motivation and Context

The SDK already returns mutable internals for many model fields, including maps, lists, arrays, and Device.timezone. Cloning Date values on every getter call adds allocation overhead without providing consistent immutability across the SDK data model surface.

💚 How did you test it?

• ./gradlew :sentry:test --tests io.sentry.BreadcrumbTest --tests io.sentry.SentryEventTest --tests io.sentry.protocol.AppTest --tests io.sentry.protocol.DeviceTest --tests io.sentry.protocol.SessionSerializationTest --tests io.sentry.SessionAdapterTest
• ./gradlew spotlessApply apiDump

📝 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

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