Upgrade Camel to spring-boot 4 (draft PR, work in progress)

[cunningt]

Description

This is a draft PR for spring-boot 4 upgrade work. At the moment it compiles, and we are working through test failures / version upgrades.

Related issues :
https://issues.apache.org/jira/browse/CAMEL-22728
https://issues.apache.org/jira/browse/CAMEL-22729
https://issues.apache.org/jira/browse/CAMEL-22730

Target

• [ x] I checked that the commit is targeting the correct branch (Camel 4 uses the main branch)

Tracking

• If this is a large change, bug fix, or code improvement, I checked there is a JIRA issue filed for the change (usually before you start working on it).

Apache Camel coding standards and style

• I checked that each commit in the pull request has a meaningful subject line and body.

• [ x] I have run mvn clean install -DskipTests locally from root folder and I have committed all auto-generated changes.

[github-actions]

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[davsclaus]

if you keep this up to date then SB 4.0.1 has been released

[cunningt]

Updated to spring-boot 4.0.2, all checks passed on 2/4/2026. Will rebase and upgrade to spring-boot 4.0.3 after release (2/19/2026).