CAMEL-18217: debugger - Allow to suspend messages

[essobedo]

Fix for https://issues.apache.org/jira/browse/CAMEL-18217

Motivation

Up to now when using the BacklogDebugger there is no easy way to suspend all messages before ensuring that all breakpoints have been defined. This can particularly be a problem when debugging an application with a very short lifetime like a test.

Modifications

• Define a system variable CAMEL_DEBUGGER_SUSPEND to suspend the message processing at startup
• Add methods attach and detach to respectively resume and suspend message processing when CAMEL_DEBUGGER_SUSPEND is set to true
• Add junit-pioneer as test dependency to be able to set the value of an environment variable within the context of a Unit test.
• Add some doc to describe it

Result

I could debug following the steps described in the blog post without the additional sleep by setting the environment variable and invoking manually attach (will be done by https://github.com/camel-tooling/camel-debug-adapter once this PR is merged).

[github-actions]

🚫 There are (likely) no components to be tested in this PR

[essobedo]

@davsclaus Using an environment variable to enable the feature is good enough for you? And if what about the name? do you have a better name in mind?

[davsclaus]

Yeah - We may consider a

mvn camel:debug goal that can set this automatic, so users can run Camel in debug mode with this out of the box.

https://github.com/apache/camel/tree/main/tooling/maven/camel-maven-plugin/src/main/java/org/apache/camel/maven

[essobedo]

Yeah - We may consider a

mvn camel:debug goal that can set this automatic, so users can run Camel in debug mode with this out of the box.

https://github.com/apache/camel/tree/main/tooling/maven/camel-maven-plugin/src/main/java/org/apache/camel/maven

@davsclaus Interesting, maybe it can be done in another PR, WDYT?

[davsclaus]

Yeah in another PR

[essobedo]

The ticket for this feature https://issues.apache.org/jira/browse/CAMEL-18223