MNG-5783 fixed slf4j is missing from ${plugin.artifacts}

Some plugins, e.g., cobertura-maven-plugin, use ${plugin.artifacts}
to setup classpath of externally launched jvms and they expect slf4j
to be available among plugin dependencies. At the same time slf4j
is already part of maven core runtime and it needs to be filtered
out from plugin and build extension realms to avoid duplicate classes
on classpath.

The fix is to move core artifact filtering from plugin dependency
resolver to class realm manager. This way ${plugin.artifacts} still
includes all compile/runtime scoped plugin dependencies but runtime
classpath only has plugin unique artifacts.

Signed-off-by: Igor Fedorenko <ifedorenko@apache.org>

maven-core/src/main/java/org/apache/maven/classrealm/DefaultClassRealmManager.java

@@ -83,6 +83,12 @@ public class DefaultClassRealmManager
 
     private final ClassRealm mavenApiRealm;
 
+    /**
+     * Patterns of artifacts provided by maven core and exported via maven api realm. These artifacts are filtered from
+     * plugin and build extensions realms to avoid presence of duplicate and possibly conflicting classes on classpath.
+     */
+    private final Set<String> providedArtifacts;
+
     @Inject
     public DefaultClassRealmManager( Logger logger, PlexusContainer container,
                                      List<ClassRealmManagerDelegate> delegates, CoreExportsProvider exports )
@@ -97,6 +103,8 @@ public DefaultClassRealmManager( Logger logger, PlexusContainer container,
         this.mavenApiRealm =
             createRealm( API_REALMID, RealmType.Core, null /* parent */, null /* parentImports */, 
                          foreignImports, null /* artifacts */ );
+
+        this.providedArtifacts = exports.get().getExportedArtifacts();
     }
 
     private ClassRealm newRealm( String id )
@@ -156,10 +164,13 @@ private ClassRealm createRealm( String baseRealmId, RealmType type, ClassLoader
         {
             for ( Artifact artifact : artifacts )
             {
-                artifactIds.add( getId( artifact ) );
+                if ( !isProvidedArtifact( artifact ) )
-                if ( artifact.getFile() != null )
                 {
-                    constituents.add( new ArtifactClassRealmConstituent( artifact ) );
+                    artifactIds.add( getId( artifact ) );
+                    if ( artifact.getFile() != null )
+                    {
+                        constituents.add( new ArtifactClassRealmConstituent( artifact ) );
+                    }
                 }
             }
         }
@@ -245,6 +256,11 @@ public ClassRealm createExtensionRealm( Plugin plugin, List<Artifact> artifacts
         return createRealm( getKey( plugin, true ), RealmType.Extension, parent, null, foreignImports, artifacts );
     }
 
+    private boolean isProvidedArtifact( Artifact artifact )
+    {
+        return providedArtifacts.contains( artifact.getGroupId() + ":" + artifact.getArtifactId() );
+    }
+
     public ClassRealm createPluginRealm( Plugin plugin, ClassLoader parent, List<String> parentImports,
                                          Map<String, ClassLoader> foreignImports, List<Artifact> artifacts )
     {

maven-core/src/main/java/org/apache/maven/plugin/internal/DefaultPluginDependenciesResolver.java

@@ -23,7 +23,6 @@
 import java.util.List;
 import java.util.Map;
 
-import org.apache.maven.ArtifactFilterManager;
 import org.apache.maven.RepositoryUtils;
 import org.apache.maven.model.Dependency;
 import org.apache.maven.model.Plugin;
@@ -54,7 +53,6 @@
 import org.eclipse.aether.resolution.DependencyResolutionException;
 import org.eclipse.aether.util.artifact.JavaScopes;
 import org.eclipse.aether.util.filter.AndDependencyFilter;
-import org.eclipse.aether.util.filter.ExclusionsDependencyFilter;
 import org.eclipse.aether.util.filter.ScopeDependencyFilter;
 import org.eclipse.aether.util.graph.selector.AndDependencySelector;
 import org.eclipse.aether.util.graph.transformer.ChainedDependencyGraphTransformer;
@@ -78,9 +76,6 @@ public class DefaultPluginDependenciesResolver
     @Requirement
     private Logger logger;
 
-    @Requirement
-    private ArtifactFilterManager artifactFilterManager;
-
     @Requirement
     private RepositorySystem repoSystem;
 
@@ -151,10 +146,7 @@ public DependencyNode resolve( Plugin plugin, Artifact pluginArtifact, Dependenc
                                    List<RemoteRepository> repositories, RepositorySystemSession session )
         throws PluginResolutionException
     {
-        DependencyFilter resolutionFilter =
+        return resolveInternal( plugin, pluginArtifact, dependencyFilter, new PlexusUtilsInjector(), repositories,
-            new ExclusionsDependencyFilter( artifactFilterManager.getCoreArtifactExcludes() );
-        resolutionFilter = AndDependencyFilter.newInstance( resolutionFilter, dependencyFilter );
-        return resolveInternal( plugin, pluginArtifact, resolutionFilter, new PlexusUtilsInjector(), repositories,
                                 session );
     }