CAMEL-23553: Fix RestRegistry lazy plugin resolution

[davsclaus]

Summary

• RestRegistry is registered as a lazy plugin via lazyAddContextPlugin(), but isContextPluginInUse() always returns false for lazy plugins. This caused VertxPlatformHttpConsumer and MultiRestConsumer to never resolve the registry — even when camel-rest was on the classpath — breaking contract-first REST services.
• Make the lazy resolution return null gracefully when camel-rest is absent (instead of throwing), so callers can use PluginHelper.getRestRegistry() directly with a null-check.

Changes

File	Change
SimpleCamelContext	Use optional resolveBootstrapService() instead of mandatory (returns null when camel-rest absent)
AbstractCamelContext	Null-check factory in createRestRegistry()
DefaultCamelContextExtension	Handle null from createRestRegistryFactory()
DefaultContextPluginManager	Remove entry when lazy supplier returns null (avoids repeated retries)
VertxPlatformHttpConsumer	Drop broken isContextPluginInUse guard, resolve directly
MultiRestConsumer	Drop broken isContextPluginInUse guard, resolve with null-check

Test plan

• mvn test -pl core/camel-base-engine — passes
• mvn test -pl components/camel-platform-http-vertx — passes
• mvn test -pl components/camel-webhook — passes
• Test contract-first REST DSL with camel-platform-http-vertx to verify services are registered in RestRegistry

Claude Code on behalf of Claus Ibsen

🤖 Generated with Claude Code

[github-actions]

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🧪 CI tested the following changed modules:

• components/camel-platform-http-vertx
• components/camel-webhook
• core/camel-base-engine

ℹ️ Dependent modules were not tested because the total number of affected modules exceeded the threshold (50). Use the test-dependents label to force testing all dependents.

Build reactor — dependencies compiled but only changed modules were tested (3 modules)

• Camel :: Base Engine
• Camel :: Platform HTTP :: Vert.x
• Camel :: Webhook

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