Do not set user properties as system properties

[gnodet]

No description provided.

[mthmulders]

I think many plugins and frameworks depend on the fact that Maven properties can be read through system properties. If we decide to drop this (undocumented) feature, it would certainly warrant a JIRA ticket that clearly mentions this breaks from previous releases.

[cstamas]

Can we NOT do this for Model v4.0.0 (hence use of Maven3 plugins) and DO THIS for Model 4.1+ maybe? As @mthmulders says, I would bet in some beer there are Maven3 plugins relying on this.

[michael-o]

Can we NOT do this for Model v4.0.0 (hence use of Maven3 plugins) and DO THIS for Model 4.1+ maybe? As @mthmulders says, I would bet in some beer there are Maven3 plugins relying on this.

How is this model related?

[michael-o]

I think many plugins and frameworks depend on the fact that Maven properties can be read through system properties. If we decide to drop this (undocumented) feature, it would certainly warrant a JIRA ticket that clearly mentions this breaks from previous releases.

This is the same as with maven.multimoduleDirectory never documented. What we should do is to us this PR and run a build of all our ITs and see what fails. I spoke about this with @slawekjaranowski last year, Invoker and friends need to be fixed first.