Maven Plugin Validation Warnings

[JackPGreen]

New versions of Maven report the following plugin validation warnings:

[WARNING]  * org.xolstice.maven.plugins:protobuf-maven-plugin:0.6.1
[WARNING]   Plugin EXTERNAL issue(s):
[WARNING]    * Plugin depends on the deprecated Maven 2.x compatibility layer, which will be not supported in Maven 4.x
[WARNING]    * Plugin should declare Maven artifacts in `provided` scope. If the plugin already declares them in `provided` scope, update the maven-plugin-plugin to latest version. Artifacts found with wrong scope: [org.apache.maven:maven-artifact:3.0, org.apache.maven:maven-plugin-api:3.0, org.apache.maven:maven-compat:3.0, org.apache.maven:maven-core:3.0]