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

Reduce the initial nesting stack in the vendored JsonWriter from int[32] to int[8].

The stack still grows on demand through the existing push() logic when serializing deeply nested payloads.

💡 Motivation and Context

JsonWriter is created for envelope headers, item headers, and serialized payloads. Sentry SDK JSON is shallow in normal use, so the upstream GSON default stack size is larger than needed for the common path.

Starting with a smaller stack reduces per-writer allocation while preserving support for deeper JSON structures.

💚 How did you test it?

• ./gradlew :sentry:test --tests io.sentry.vendor.gson.stream.JsonWriterTest
• ./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.