Upgrade to maven 3.x and avoid using deprecated API

[gnodet]

Ground work for https://issues.apache.org/jira/browse/MNG-7266.

Upgrading to maven 3.1.1 is not really possible as the ProjectArtifactFactory has been introduced in 3.2.x branch and is required in order to get rid of the deprecated MavenProject.createArtifacts(xxx) method.

The ModelInheritanceAssembler and ModelUtils have been imported from maven-compat in order to not depend on that deprecated jar.

[cstamas]

Personally I see this as a proof that our baseline of 3.1.1 is simply wrong/broken idea.

I am +1 on this change, but we should reconcile what is the proper baseline (I am in "the higher the better" ballpark). We should go 3.6 as baseline (and even then, we cover 3.6.x and 3.8.x that is still a huge time-span).

[slachiewicz]

To me, 3.3.9 sounds like reasonable minimum for next year.

[gnodet]

Personally I see this as a proof that our baseline of 3.1.1 is simply wrong/broken idea.

I am +1 on this change, but we should reconcile what is the proper baseline (I am in "the higher the better" ballpark). We should go 3.6 as baseline (and even then, we cover 3.6.x and 3.8.x that is still a huge time-span).

I don't have a strong opinion about forcing 3.6.x or 3.8.x, but I certainly think we should not forbid that. I'll merge the PR, we can always bump the maven version to a higher one if we want to align plugins.

[slachiewicz]

it will also (at some time) effectively bump minimum maven for apache-maven parent pom: https://github.com/apache/maven-apache-parent/blob/01d2517a3d8e302270b6f9bf182db5659e5c0a11/pom.xml#L249-L253

[rfscholte]

This commit broke the master the branch on https://ci-maven.apache.org/job/Maven/job/maven-box/job/maven-remote-resources-plugin/job/master/ ( you can ignore Build XX-jdk8-m3.5.x_site, I will fix that afterwards )

[rfscholte]

Also, such a change deserves a JIRA ticket, including the message [MRRESOURCES-118] Require Maven 3.2.0.
I've created the ticket.