[MNG-5561] Plugin relocation loses configuration

Previously, to locate plugin configuration in a project the plugin descriptor
was read first and then the GA were extracted. This always worked because the
GA from the model and the GA from plugin descriptor (plugin.xml) were identical.
When a plugin is relocated the target artifact is read, thus its plugin
descriptor as well. Naturally, the GA of new (relocated) does not correspond to
the old (static) one in the model. Therefore, the configuration is not found.
New approach is to use the original plugin GA to locate the configuration in
the model regardless of the relocation.

This closes #642

maven-core/src/main/java/org/apache/maven/lifecycle/internal/DefaultMojoExecutionConfigurator.java

@@ -44,9 +44,9 @@ public class DefaultMojoExecutionConfigurator
     @Override
     public void configure( MavenProject project, MojoExecution mojoExecution, boolean allowPluginLevelConfig )
     {
-        String g = mojoExecution.getGroupId();
+        String g = mojoExecution.getPlugin().getGroupId();
 
-        String a = mojoExecution.getArtifactId();
+        String a = mojoExecution.getPlugin().getArtifactId();
 
         Plugin plugin = findPlugin( g, a, project.getBuildPlugins() );
 

maven-core/src/test/java/org/apache/maven/lifecycle/internal/stub/BuildPluginManagerStub.java

@@ -42,7 +42,7 @@ public PluginDescriptor loadPlugin( Plugin plugin, List<RemoteRepository> reposi
     public MojoDescriptor getMojoDescriptor( Plugin plugin, String goal, List<RemoteRepository> repositories,
                                              RepositorySystemSession session )
     {
-        return MojoExecutorStub.createMojoDescriptor( plugin.getKey() );
+        return MojoExecutorStub.createMojoDescriptor( plugin );
     }
 
     public ClassRealm getPluginRealm( MavenSession session, PluginDescriptor pluginDescriptor )

maven-core/src/test/java/org/apache/maven/lifecycle/internal/stub/MojoExecutorStub.java

@@ -25,6 +25,7 @@
 import org.apache.maven.lifecycle.internal.ProjectIndex;
 import org.apache.maven.plugin.BuildPluginManager;
 import org.apache.maven.plugin.MavenPluginManager;
+import org.apache.maven.model.Plugin;
 import org.apache.maven.plugin.MojoExecution;
 import org.apache.maven.plugin.descriptor.MojoDescriptor;
 import org.apache.maven.plugin.descriptor.PluginDescriptor;
@@ -67,12 +68,14 @@ public void execute( MavenSession session, List<MojoExecution> mojoExecutions, P
     }
 
 
-    public static MojoDescriptor createMojoDescriptor( String mojoDescription )
+    public static MojoDescriptor createMojoDescriptor( Plugin plugin )
     {
         final PluginDescriptor descriptor = new PluginDescriptor();
-        descriptor.setArtifactId( mojoDescription );
+        descriptor.setGroupId( plugin.getGroupId() );
+        descriptor.setArtifactId( plugin.getArtifactId() );
+        descriptor.setPlugin( plugin );
+        descriptor.setVersion( plugin.getVersion() );
         final MojoDescriptor mojoDescriptor = new MojoDescriptor();
-        mojoDescriptor.setDescription( mojoDescription );
         mojoDescriptor.setPluginDescriptor( descriptor );
         return mojoDescriptor;
     }