[MSHARED-817] Change eclipse aether dependency scope to provided

[belingueres]

• Changed eclipse aether dependency to provided scope.
• Removed shading of aether classes.
• Added method to import aether library inside TransferUtils to use from
  a plugin.
• Modified ProjectDeployerMojo and ProjectInstallerMojo plugins used for
  ITs.

[rfscholte]

This commit looks kind of dangerous to me. The integration goals show how a any plugin should use this library, the classRealm is for Maven internal only and is public due to design restrictions.

[belingueres]

@rfscholte Would it be OK if the classRealm handling is inside the artifact-transfer library instead of inside the plugin's code?

[rfscholte]

That would be better, bet this library should not assume it is always used within a Maven Classrealm. There should be a good fallback.

[belingueres]

Hi @rfscholte. I tracked this issue and it is related to MNG-5901, where the package org.eclipse.aether.util was removed from the extensions.xml exports.
I've tested it adding org.eclipse.aether.util back again into extensions.xml in 3.6.2-SNAPSHOT: Core ITs show all OK, and tested with maven-project-deployer-plugin (from artifact-transfer) and it works OK without importing the package as part of the library (3.6.2-SNAPSHOT only, previous mvn versions still need the package import).

[rfscholte]

That's great news. I guess this means that plugins/extensions trying to upload/download are forced to use maven-artifact-transfer. That's probably fine assuming this is done by our own maven-plugins

[belingueres]

So should we open a new issue to revert MNG-5901?

[rfscholte]

Changes look interesting and would solve the shading issue that's still required. Just a small number of remarks.