[gnodet]

Backport of #28197

Cherry-pick of b7594f0 to camel-4.22.x.
Conflicts resolved automatically by backport bot agent.

[gnodet-bot]

Well-engineered fix for a real MQTT QoS 1 message delivery bug. The rollback() method correctly captures client into a local variable before the null check, which protects against the NPE race with doStop() that nulls the field. The stopClient guard in rollback() is semantically correct despite the field name being a bit misleading. No concerns — the concurrency model is sound.

This review was generated by an AI agent, Hermès on behalf of @gnodet.

[github-actions]

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[davsclaus]

Not a straight cherry-pick: PahoMqtt5Consumer.doStart/doStop are adapted because camel-4.22.x does not have CAMEL-24465 (cleanup after a failed start). The adaptation looks right: the reconnect executor is created inside the if (client == null) block, and on 4.22.x a failed start() calls stop(), whose doStop shuts the executor down, so nothing leaks without main's catch block. The test and configuration changes are the same as #28197.

The upgrade note goes into camel-4x-upgrade-guide-4_22.adoc on the branch; the same entry is still needed in the 4_22 guide on main.

Approving, to merge once CI is green.

Claude Code on behalf of @davsclaus.

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

[github-actions]

🧪 CI tested the following changed modules:

• catalog/camel-catalog
• components/camel-paho-mqtt5
• docs
• dsl/camel-componentdsl
• dsl/camel-endpointdsl

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🔬 Scalpel shadow comparison — Scalpel: 13 tested, 25 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 13 modules (5 direct + 8 downstream), skip tests for 25 (generated code, meta-modules)

Modules Scalpel would test (13)

• camel-catalog
• camel-componentdsl
• camel-endpointdsl
• camel-jbang-mcp
• camel-jbang-plugin-mcp
• camel-jbang-plugin-route-parser
• camel-jbang-plugin-tui
• camel-jbang-plugin-validate
• camel-launcher-container
• camel-paho-mqtt5
• camel-yaml-dsl-validator
• camel-yaml-dsl-validator-maven-plugin
• docs

Modules with tests skipped (25)

• apache-camel
• camel-allcomponents
• camel-catalog-console
• camel-catalog-lucene
• camel-catalog-maven
• camel-catalog-suggest
• camel-csimple-maven-plugin
• 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
• dummy-component

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

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 :: Kamelet Main
• Camel :: Launcher
• Camel :: Launcher :: Container
• Camel :: Paho MQTT 5
• 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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