CAMEL-24305: Fix autowiring of KafkaClientFactory via addComponent()

[gnodet]

Summary

Claude Code on behalf of gnodet

Fixes CAMEL-24305: KafkaComponent does not autowire a custom KafkaClientFactory bean when the component is registered via addComponent() (the path used by Spring Boot).

Root Cause

When a component is registered via CamelContext.addComponent(), the lifecycle order is:

1. ServiceHelper.initService(component) — calls doBuild() + doInit()
2. postInitComponent() — triggers autowiring via LifecycleStrategySupport.doAutoWire()

Since KafkaComponent.doInit() was creating a DefaultKafkaClientFactory in step 1, the field was already non-null when autowiring checked it in step 2, and the custom factory was silently skipped.

This is a regression from CAMEL-17262 (commit 74c5a4ad2a7), which reintroduced the bug originally fixed in CAMEL-16500 (commit 5ae05407c02).

Fix

• KafkaComponent: Move default KafkaClientFactory creation from doInit() to doStart(), giving the autowiring lifecycle strategy time to inject a custom factory before the default is created. This follows the same pattern used by MapstructComponent and VertxHttpComponent.
• KafkaEndpoint: Restore the DefaultKafkaClientFactory fallback in doBuild() (originally from CAMEL-16500) for resilience when the endpoint builds before the component starts.

Tests

• Added testKafkaComponentAutowiringViaAddComponent() — exercises the addComponent() path with a custom KafkaClientFactory registered in the registry, verifying autowiring works
• Added testKafkaComponentDefaultFactoryWhenNoneRegistered() — verifies the default factory is still created when no custom factory is available
• Existing testKafkaComponentAutowiring() continues to pass (exercises the getComponent() path)
• All 196 unit tests in camel-kafka pass with 0 failures

🤖 Generated with Claude Code

[github-actions]

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[github-actions]

🧪 CI tested the following changed modules:

• components/camel-kafka

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🔬 Scalpel shadow comparison — Scalpel: 9 tested, 29 compile-only — current: 9 all tested

Maveniverse Scalpel detected 38 affected modules (current approach: 9).

⚠️ Modules only in Scalpel (29)

• apache-camel
• camel-allcomponents
• camel-catalog
• camel-catalog-console
• camel-catalog-lucene
• camel-catalog-maven
• camel-catalog-suggest
• camel-componentdsl
• camel-csimple-maven-plugin
• camel-endpointdsl
• camel-endpointdsl-support
• camel-itest
• camel-jbang-core
• camel-jbang-it
• camel-jbang-main
• camel-jbang-plugin-edit
• camel-jbang-plugin-generate
• camel-jbang-plugin-kubernetes
• camel-jbang-plugin-test
• camel-kamelet-main
• camel-launcher
• camel-report-maven-plugin
• camel-route-parser
• camel-yaml-dsl
• camel-yaml-dsl-deserializers
• camel-yaml-dsl-maven-plugin
• coverage
• docs
• dummy-component

Skip-tests mode would test 9 modules (1 direct + 8 downstream), skip tests for 29 (generated code, meta-modules)

Modules Scalpel would test (9)

• camel-jbang-mcp
• camel-jbang-plugin-mcp
• camel-jbang-plugin-route-parser
• camel-jbang-plugin-tui
• camel-jbang-plugin-validate
• camel-kafka
• camel-launcher-container
• camel-yaml-dsl-validator
• camel-yaml-dsl-validator-maven-plugin

Modules with tests skipped (29)

• apache-camel
• camel-allcomponents
• camel-catalog
• camel-catalog-console
• camel-catalog-lucene
• camel-catalog-maven
• camel-catalog-suggest
• camel-componentdsl
• camel-csimple-maven-plugin
• camel-endpointdsl
• camel-endpointdsl-support
• camel-itest
• camel-jbang-core
• camel-jbang-it
• camel-jbang-main
• camel-jbang-plugin-edit
• camel-jbang-plugin-generate
• camel-jbang-plugin-kubernetes
• camel-jbang-plugin-test
• camel-kamelet-main
• camel-launcher
• camel-report-maven-plugin
• camel-route-parser
• camel-yaml-dsl
• camel-yaml-dsl-deserializers
• camel-yaml-dsl-maven-plugin
• coverage
• docs
• dummy-component

ℹ️ Shadow mode — Scalpel observes but does not affect test execution. Learn more

⚠️ Some tests are disabled on GitHub Actions (@DisabledIfSystemProperty(named = "ci.env.name")) and require manual verification:

• components/camel-kafka: 2 test(s) disabled on GitHub Actions

All tested modules (38 modules)

• Camel :: All Components Sync point
• Camel :: Assembly
• Camel :: Catalog :: CSimple Maven Plugin (deprecated)
• Camel :: Catalog :: Camel Catalog
• Camel :: Catalog :: Camel Report Maven Plugin
• Camel :: Catalog :: Camel Route Parser
• Camel :: Catalog :: Console
• Camel :: Catalog :: Dummy Component
• Camel :: Catalog :: Lucene (deprecated)
• Camel :: Catalog :: Maven
• Camel :: Catalog :: Suggest
• Camel :: Component DSL
• Camel :: Coverage
• Camel :: Docs
• Camel :: Endpoint DSL
• Camel :: Endpoint DSL :: Support
• Camel :: Integration Tests
• Camel :: JBang :: Core
• Camel :: JBang :: Integration tests
• Camel :: JBang :: MCP
• Camel :: JBang :: Main
• Camel :: JBang :: Plugin :: Edit
• Camel :: JBang :: Plugin :: Generate
• Camel :: JBang :: Plugin :: Kubernetes
• Camel :: JBang :: Plugin :: MCP
• Camel :: JBang :: Plugin :: Route Parser
• Camel :: JBang :: Plugin :: TUI
• Camel :: JBang :: Plugin :: Testing
• Camel :: JBang :: Plugin :: Validate
• Camel :: Kafka
• Camel :: Kamelet Main
• Camel :: Launcher
• Camel :: Launcher :: Container
• Camel :: YAML DSL
• Camel :: YAML DSL :: Deserializers
• Camel :: YAML DSL :: Maven Plugins
• Camel :: YAML DSL :: Validator
• Camel :: YAML DSL :: Validator Maven Plugin

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⚙️ View full build and test results

[gnodet]

Looks good ✅

Correct fix for a real regression where CAMEL-17262 re-introduced the autowiring bug originally fixed in CAMEL-16500. The root cause is clear: creating the default KafkaClientFactory in doInit() blocks autowiring because the lifecycle ordering in addComponent() is:

1. ServiceHelper.initService → doInit() (default factory created here)
2. postInitComponent → onComponentAdd → doAutoWire() (skips non-null fields)

Moving default creation to doStart() allows autowiring to inject a custom factory first. This follows the same pattern used in MapstructComponent and VertxHttpComponent.

Key observations:

• The defensive fallback in KafkaEndpoint.doBuild() is appropriate — since doBuild() runs during endpoint creation (before component start in some lifecycle paths), the component's factory may still be null at that point
• kafkaManualCommitFactory doesn't need the same treatment since no default is ever created for it
• Good test coverage with the new KafkaAutowireTest

CI passes on both JDK 17 and JDK 25.

This review was generated by an AI agent and may contain inaccuracies. Please verify all suggestions before applying.

Claude Code on behalf of Guillaume Nodet

[gnodet]

Review Summary (informational — not a formal approval)

Correct fix for a verified regression where CAMEL-17262 re-introduced the autowiring bug originally fixed in CAMEL-16500. The lifecycle analysis is accurate, the fix follows established component patterns, and the test coverage is thorough.

Regression chain (verified via git history)

1. CAMEL-16500 (commit 5ae05407c02) — Fixed autowiring by removing the field initializer = new DefaultKafkaClientFactory() and adding an endpoint-level fallback
2. CAMEL-17262 (commit 74c5a4ad2a7) — Introduced doInit() with default factory creation, which re-blocked autowiring in the addComponent() path
3. This PR — Correctly moves default creation to doStart() (after autowiring has run)

Key observations

• The doStart() approach follows the same pattern used by MapstructComponent and VertxHttpComponent
• Moving the kafkaManualCommitFactory warning to doStart() avoids false alarms in the addComponent() path
• The defensive fallback new DefaultKafkaClientFactory() in doBuild() is benign since DefaultKafkaClientFactory is stateless
• Tests are well-designed: testKafkaComponentAutowiringViaAddComponent() directly exercises the failing code path

Minor convention note

New test methods use JUnit assertions instead of AssertJ. Consistent with the existing test file, but project-wide preference is AssertJ.

Note: This is an informational review only — an agent cannot approve its operator's own PRs. Human review is required.

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This review was generated by an AI agent and may contain inaccuracies. Please verify all suggestions before applying.

Claude Code on behalf of @gnodet