feat: spring-boot-4x support, includes spring-kafka 4x

[osoykan]

PR: Add Spring Boot 4.x support and improve DX

Summary

Add Spring Boot 4.x support with unified modules and improve developer experience.

Changes

Spring Boot 4.x Support

• Single stove-spring-testing-e2e and stove-spring-testing-e2e-kafka modules now support Spring Boot 2.7+, 3.x, and 4.x
• Uses reflection-based sendCompatible() to handle Kafka API differences across versions

Developer Experience

• KafkaSystemOptions.ops now defaults to defaultKafkaOps()
• Added runtime checks with clear error messages when Spring Boot or Spring Kafka is missing from classpath

[Copilot]

Pull request overview

This pull request adds support for Spring Boot 4.x and Spring Kafka 4.x by creating new dedicated modules (stove-spring-4x-testing-e2e and stove-spring-4x-testing-e2e-kafka) alongside the existing Spring Boot 2.x/3.x modules. The changes include compatibility adjustments for API differences between versions and a working example application.

Key Changes

• Added type constraints (K : Any, V : Any) to TestSystemKafkaInterceptor for Spring Kafka 4.x compatibility
• Created new Spring 4x modules with updated APIs (using BeanRegistrarDsl instead of BeanDefinitionDsl)
• Implemented KafkaTemplateCompatibility to handle Spring Kafka 4.x's CompletableFuture-based send API
• Added Jackson 3 support (tools.jackson) for Spring Boot 4.x example
• Included comprehensive test suites for Kafka with string and protobuf serialization

Reviewed changes

Copilot reviewed 42 out of 43 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
starters/spring/stove-spring-testing-e2e-kafka/src/main/kotlin/com/trendyol/stove/testing/e2e/kafka/TestSystemInterceptor.kt	Added non-nullable type constraints to generic parameters
starters/spring/stove-spring-4x-testing-e2e/src/main/kotlin/com/trendyol/stove/testing/e2e/BaseApplicationContextInitializer.kt	New bean registration API using BeanRegistrarDsl
starters/spring/stove-spring-4x-testing-e2e-kafka/src/main/kotlin/com/trendyol/stove/testing/e2e/kafka/KafkaTemplateCompatibility.kt	Compatibility layer for async send operations
starters/spring/stove-spring-4x-testing-e2e-kafka/src/main/kotlin/com/trendyol/stove/testing/e2e/kafka/TestSystemInterceptor.kt	Spring 4x version with updated type constraints
examples/spring-4x-example/	Complete example application demonstrating Spring Boot 4.x with Kafka
gradle/libs.versions.toml	Added Spring Boot 4.x and Jackson 3 dependencies
settings.gradle.kts	Registered new modules in project structure

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[codecov]

Codecov Report

❌ Patch coverage is 79.81651% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.00%. Comparing base (cc8dde7) to head (73a4598).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...endyol/stove/testing/e2e/SpringBootVersionCheck.kt	9.09%	10 Missing ⚠️
...stove/testing/e2e/kafka/SpringKafkaVersionCheck.kt	25.00%	3 Missing ⚠️
...c/main/kotlin/stove/spring/example4x/ExampleApp.kt	50.00%	2 Missing ⚠️
...ve/testing/e2e/kafka/KafkaTemplateCompatibility.kt	81.81%	1 Missing and 1 partial ⚠️
...in/com/trendyol/stove/testing/e2e/kafka/Options.kt	50.00%	2 Missing ⚠️
...frastructure/messaging/kafka/KafkaConfiguration.kt	96.66%	0 Missing and 1 partial ⚠️
...l/stove/testing/e2e/kafka/TestSystemInterceptor.kt	50.00%	1 Missing ⚠️
...kotlin/com/trendyol/stove/testing/e2e/registrar.kt	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #934      +/-   ##
==========================================
+ Coverage   76.82%   78.00%   +1.17%     
==========================================
  Files          91      111      +20     
  Lines        2969     3655     +686     
  Branches      242      306      +64     
==========================================
+ Hits         2281     2851     +570     
- Misses        561      624      +63     
- Partials      127      180      +53     

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