CAMEL-21572: fix java.lang.NullPointerException when using SetHeader and Stub

[bartoszpop]

CAMEL-21572: fix java.lang.NullPointerException when using SetHeader and Stub

Description

SetHeader with a simple expression causes NullPointerException to be thrown because for runtime other than default (kamelet-main) JBang uses Stub instead of the actual component which produces null.

        - setHeader: 
            id: setHeader-c0db
            name: SampleUUID
            expression: 
              simple: 
                id: simple-536b
                expression: >-
                  This is a sample UUID: 
                  ${bean:type:java.util.UUID?method=randomUUID}

Target

• I checked that the commit is targeting the correct branch (note that Camel 3 uses camel-3.x, whereas 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.

• 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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