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Posted to commits@maven.apache.org by cs...@apache.org on 2022/04/04 15:12:57 UTC

[maven-resolver] 01/01: [MRESOLVER-248] Make BF and DF collectors coexists

This is an automated email from the ASF dual-hosted git repository.

cstamas pushed a commit to branch MRESOLVER-248-collector-bf-df-coexists
in repository https://gitbox.apache.org/repos/asf/maven-resolver.git

commit d486deaedfc91d4b2175b6aeed58b57aa6a12156
Author: Tamas Cservenak <ta...@cservenak.net>
AuthorDate: Mon Apr 4 17:12:30 2022 +0200

    [MRESOLVER-248] Make BF and DF collectors coexists
---
 .../eclipse/aether/impl/guice/AetherModule.java    |  17 +
 .../impl/collect/CachingArtifactTypeRegistry.java  |   2 +-
 .../aether/internal/impl/collect/DataPool.java     |  20 +-
 .../DefaultDependencyCollectionContext.java        |   4 +-
 .../impl/collect/DefaultDependencyCollector.java   | 899 +--------------------
 ...efaultDependencyGraphTransformationContext.java |   4 +-
 .../impl/collect/DefaultVersionFilterContext.java  |   4 +-
 ...ipper.java => DependencyCollectorDelegate.java} |  30 +-
 .../BfDependencyCollector.java}                    |  62 +-
 .../BfDependencyCycle.java}                        |   7 +-
 .../BfProcessingContext.java}                      |  22 +-
 .../DefaultDependencyResolutionSkipper.java        |  20 +-
 .../{ => bf}/NeverDependencyResolutionSkipper.java |   8 +-
 .../BfDependencyCollectorTest.java}                |  27 +-
 .../BfDependencyCollectorUseSkipTest.java}         |  14 +-
 .../BfDependencyCycleTest.java}                    |  12 +-
 .../{ => bf}/DependencyResolutionSkipperTest.java  |  14 +-
 17 files changed, 167 insertions(+), 999 deletions(-)

diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/impl/guice/AetherModule.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/impl/guice/AetherModule.java
index 9629dc97..7d7f9f0b 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/impl/guice/AetherModule.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/impl/guice/AetherModule.java
@@ -48,6 +48,8 @@ import org.eclipse.aether.internal.impl.checksum.Sha1ChecksumAlgorithmFactory;
 import org.eclipse.aether.internal.impl.checksum.Sha256ChecksumAlgorithmFactory;
 import org.eclipse.aether.internal.impl.checksum.Sha512ChecksumAlgorithmFactory;
 import org.eclipse.aether.internal.impl.checksum.DefaultChecksumAlgorithmFactorySelector;
+import org.eclipse.aether.internal.impl.collect.DependencyCollectorDelegate;
+import org.eclipse.aether.internal.impl.collect.bf.BfDependencyCollector;
 import org.eclipse.aether.internal.impl.synccontext.DefaultSyncContextFactory;
 import org.eclipse.aether.internal.impl.synccontext.named.NamedLockFactorySelector;
 import org.eclipse.aether.internal.impl.synccontext.named.SimpleNamedLockFactorySelector;
@@ -132,8 +134,12 @@ public class AetherModule
                 .to( DefaultRepositorySystem.class ).in( Singleton.class );
         bind( ArtifactResolver.class ) //
                 .to( DefaultArtifactResolver.class ).in( Singleton.class );
+
         bind( DependencyCollector.class ) //
                 .to( DefaultDependencyCollector.class ).in( Singleton.class );
+        bind( DependencyCollectorDelegate.class ).annotatedWith( Names.named( BfDependencyCollector.NAME ) )
+                .to( BfDependencyCollector.class ).in( Singleton.class );
+
         bind( Deployer.class ) //
                 .to( DefaultDeployer.class ).in( Singleton.class );
         bind( Installer.class ) //
@@ -223,6 +229,17 @@ public class AetherModule
         return providedChecksumsSource;
     }
 
+    @Provides
+    @Singleton
+    Map<String, DependencyCollectorDelegate> dependencyCollectorDelegates(
+            @Named( BfDependencyCollector.NAME ) DependencyCollectorDelegate bf
+    )
+    {
+        Map<String, DependencyCollectorDelegate> providedChecksumsSource = new HashMap<>();
+        providedChecksumsSource.put( BfDependencyCollector.NAME, bf );
+        return providedChecksumsSource;
+    }
+
     @Provides
     @Singleton
     Map<String, ChecksumAlgorithmFactory> provideChecksumTypes(
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/CachingArtifactTypeRegistry.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/CachingArtifactTypeRegistry.java
index a2602344..bb03b142 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/CachingArtifactTypeRegistry.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/CachingArtifactTypeRegistry.java
@@ -29,7 +29,7 @@ import org.eclipse.aether.artifact.ArtifactTypeRegistry;
 /**
  * A short-lived artifact type registry that caches results from a presumedly slower type registry.
  */
-class CachingArtifactTypeRegistry
+public class CachingArtifactTypeRegistry
     implements ArtifactTypeRegistry
 {
 
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DataPool.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DataPool.java
index 4a145558..d54a5634 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DataPool.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DataPool.java
@@ -49,7 +49,7 @@ import org.eclipse.aether.version.VersionConstraint;
 
 /**
  */
-final class DataPool
+public final class DataPool
 {
 
     private static final String ARTIFACT_POOL = DataPool.class.getName() + "$Artifact";
@@ -58,7 +58,7 @@ final class DataPool
 
     private static final String DESCRIPTORS = DataPool.class.getName() + "$Descriptors";
 
-    static final ArtifactDescriptorResult NO_DESCRIPTOR =
+    public static final ArtifactDescriptorResult NO_DESCRIPTOR =
         new ArtifactDescriptorResult( new ArtifactDescriptorRequest() );
 
     private ObjectPool<Artifact> artifacts;
@@ -72,7 +72,7 @@ final class DataPool
     private final Map<Object, List<DependencyNode>> nodes = new HashMap<>( 256 );
 
     @SuppressWarnings( "unchecked" )
-    DataPool( RepositorySystemSession session )
+    public DataPool( RepositorySystemSession session )
     {
         RepositoryCache cache = session.getCache();
 
@@ -121,12 +121,12 @@ final class DataPool
         return dependencies.intern( dependency );
     }
 
-    Object toKey( ArtifactDescriptorRequest request )
+    public Object toKey( ArtifactDescriptorRequest request )
     {
         return request.getArtifact();
     }
 
-    ArtifactDescriptorResult getDescriptor( Object key, ArtifactDescriptorRequest request )
+    public ArtifactDescriptorResult getDescriptor( Object key, ArtifactDescriptorRequest request )
     {
         Descriptor descriptor = descriptors.get( key );
         if ( descriptor != null )
@@ -136,22 +136,22 @@ final class DataPool
         return null;
     }
 
-    void putDescriptor( Object key, ArtifactDescriptorResult result )
+    public void putDescriptor( Object key, ArtifactDescriptorResult result )
     {
         descriptors.put( key, new GoodDescriptor( result ) );
     }
 
-    void putDescriptor( Object key, ArtifactDescriptorException e )
+    public void putDescriptor( Object key, ArtifactDescriptorException e )
     {
         descriptors.put( key, BadDescriptor.INSTANCE );
     }
 
-    Object toKey( VersionRangeRequest request )
+    public Object toKey( VersionRangeRequest request )
     {
         return new ConstraintKey( request );
     }
 
-    VersionRangeResult getConstraint( Object key, VersionRangeRequest request )
+    public VersionRangeResult getConstraint( Object key, VersionRangeRequest request )
     {
         Constraint constraint = constraints.get( key );
         if ( constraint != null )
@@ -161,7 +161,7 @@ final class DataPool
         return null;
     }
 
-    void putConstraint( Object key, VersionRangeResult result )
+    public void putConstraint( Object key, VersionRangeResult result )
     {
         constraints.put( key, new Constraint( result ) );
     }
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectionContext.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectionContext.java
index 3bf4fe1a..0c66fa79 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectionContext.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectionContext.java
@@ -29,7 +29,7 @@ import org.eclipse.aether.graph.Dependency;
 /**
  * @see DefaultDependencyCollector
  */
-final class DefaultDependencyCollectionContext
+public final class DefaultDependencyCollectionContext
     implements DependencyCollectionContext
 {
 
@@ -41,7 +41,7 @@ final class DefaultDependencyCollectionContext
 
     private List<Dependency> managedDependencies;
 
-    DefaultDependencyCollectionContext( RepositorySystemSession session, Artifact artifact,
+    public DefaultDependencyCollectionContext( RepositorySystemSession session, Artifact artifact,
                                                Dependency dependency, List<Dependency> managedDependencies )
     {
         this.session = session;
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollector.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollector.java
index a895bb9b..1c0b6e95 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollector.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollector.java
@@ -19,914 +19,75 @@ package org.eclipse.aether.internal.impl.collect;
  * under the License.
  */
 
-import java.util.ArrayDeque;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Queue;
-
-import static java.util.Objects.requireNonNull;
-import static org.eclipse.aether.internal.impl.collect.DefaultDependencyCycle.find;
-
 import javax.inject.Inject;
 import javax.inject.Named;
 import javax.inject.Singleton;
 
-import org.eclipse.aether.DefaultRepositorySystemSession;
-import org.eclipse.aether.RepositoryException;
+import java.util.HashMap;
+import java.util.Map;
+
 import org.eclipse.aether.RepositorySystemSession;
-import org.eclipse.aether.RequestTrace;
-import org.eclipse.aether.artifact.Artifact;
-import org.eclipse.aether.artifact.ArtifactProperties;
 import org.eclipse.aether.collection.CollectRequest;
 import org.eclipse.aether.collection.CollectResult;
 import org.eclipse.aether.collection.DependencyCollectionException;
-import org.eclipse.aether.collection.DependencyGraphTransformer;
-import org.eclipse.aether.collection.DependencyManagement;
-import org.eclipse.aether.collection.DependencyManager;
-import org.eclipse.aether.collection.DependencySelector;
-import org.eclipse.aether.collection.DependencyTraverser;
-import org.eclipse.aether.collection.VersionFilter;
-import org.eclipse.aether.graph.DefaultDependencyNode;
-import org.eclipse.aether.graph.Dependency;
-import org.eclipse.aether.graph.DependencyNode;
-import org.eclipse.aether.graph.Exclusion;
-import org.eclipse.aether.impl.ArtifactDescriptorReader;
 import org.eclipse.aether.impl.DependencyCollector;
-import org.eclipse.aether.impl.DependencyResolutionSkipper;
-import org.eclipse.aether.impl.RemoteRepositoryManager;
-import org.eclipse.aether.impl.VersionRangeResolver;
-import org.eclipse.aether.repository.ArtifactRepository;
-import org.eclipse.aether.repository.RemoteRepository;
-import org.eclipse.aether.resolution.ArtifactDescriptorException;
-import org.eclipse.aether.resolution.ArtifactDescriptorRequest;
-import org.eclipse.aether.resolution.ArtifactDescriptorResult;
-import org.eclipse.aether.resolution.VersionRangeRequest;
-import org.eclipse.aether.resolution.VersionRangeResolutionException;
-import org.eclipse.aether.resolution.VersionRangeResult;
+import org.eclipse.aether.internal.impl.collect.bf.BfDependencyCollector;
 import org.eclipse.aether.spi.locator.Service;
 import org.eclipse.aether.spi.locator.ServiceLocator;
 import org.eclipse.aether.util.ConfigUtils;
-import org.eclipse.aether.util.graph.manager.DependencyManagerUtils;
-import org.eclipse.aether.util.graph.transformer.TransformationContextKeys;
-import org.eclipse.aether.version.Version;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+
+import static java.util.Objects.requireNonNull;
 
 /**
+ *
  */
 @Singleton
 @Named
 public class DefaultDependencyCollector
-    implements DependencyCollector, Service
+        implements DependencyCollector, Service
 {
+    private static final String CONFIG_PROP_COLLECTOR_IMPL = "aether.collector.impl";
 
-    /**
-     * The key in the repository session's {@link org.eclipse.aether.RepositorySystemSession#getConfigProperties()
-     * configuration properties} used to store a {@link Boolean} flag controlling the resolver's skip mode.
-     *
-     * @since 1.8.0
-     */
-    public static final String CONFIG_PROP_USE_SKIP = "aether.dependencyCollector.useSkip";
+    private static final String DEFAULT_COLLECTOR_IMPL = BfDependencyCollector.NAME;
+
+    private final Map<String, DependencyCollectorDelegate> delegates;
 
     /**
-     * The default value for {@link #CONFIG_PROP_USE_SKIP}, {@code true}.
+     * Default ctor for SL.
      *
-     * @since 1.8.0
+     * @deprecated SL is to be removed.
      */
-    public static final boolean CONFIG_PROP_USE_SKIP_DEFAULT = true;
-
-    private static final String CONFIG_PROP_MAX_EXCEPTIONS = "aether.dependencyCollector.maxExceptions";
-
-    private static final int CONFIG_PROP_MAX_EXCEPTIONS_DEFAULT = 50;
-
-    private static final String CONFIG_PROP_MAX_CYCLES = "aether.dependencyCollector.maxCycles";
-
-    private static final int CONFIG_PROP_MAX_CYCLES_DEFAULT = 10;
-
-    private static final Logger LOGGER = LoggerFactory.getLogger( DefaultDependencyCollector.class );
-
-    private RemoteRepositoryManager remoteRepositoryManager;
-
-    private ArtifactDescriptorReader descriptorReader;
-
-    private VersionRangeResolver versionRangeResolver;
-
+    @Deprecated
     public DefaultDependencyCollector()
     {
-        // enables default constructor
+        this.delegates = new HashMap<>();
     }
 
     @Inject
-    DefaultDependencyCollector( RemoteRepositoryManager remoteRepositoryManager,
-                                ArtifactDescriptorReader artifactDescriptorReader,
-                                VersionRangeResolver versionRangeResolver )
+    public DefaultDependencyCollector( Map<String, DependencyCollectorDelegate> delegates )
     {
-        setRemoteRepositoryManager( remoteRepositoryManager );
-        setArtifactDescriptorReader( artifactDescriptorReader );
-        setVersionRangeResolver( versionRangeResolver );
+        this.delegates = requireNonNull( delegates );
     }
 
+    @Override
     public void initService( ServiceLocator locator )
     {
-        setRemoteRepositoryManager( locator.getService( RemoteRepositoryManager.class ) );
-        setArtifactDescriptorReader( locator.getService( ArtifactDescriptorReader.class ) );
-        setVersionRangeResolver( locator.getService( VersionRangeResolver.class ) );
-    }
-
-    public DefaultDependencyCollector setRemoteRepositoryManager( RemoteRepositoryManager remoteRepositoryManager )
-    {
-        this.remoteRepositoryManager =
-                requireNonNull( remoteRepositoryManager, "remote repository provider cannot be null" );
-        return this;
-    }
-
-    public DefaultDependencyCollector setArtifactDescriptorReader( ArtifactDescriptorReader artifactDescriptorReader )
-    {
-        descriptorReader = requireNonNull( artifactDescriptorReader, "artifact descriptor reader cannot be null" );
-        return this;
+        BfDependencyCollector bf = new BfDependencyCollector();
+        bf.initService( locator );
+        this.delegates.put( BfDependencyCollector.NAME, bf );
     }
 
-    public DefaultDependencyCollector setVersionRangeResolver( VersionRangeResolver versionRangeResolver )
-    {
-        this.versionRangeResolver =
-                requireNonNull( versionRangeResolver, "version range resolver cannot be null" );
-        return this;
-    }
-
-    @SuppressWarnings( "checkstyle:methodlength" )
+    @Override
     public CollectResult collectDependencies( RepositorySystemSession session, CollectRequest request )
-        throws DependencyCollectionException
-    {
-        requireNonNull( session, "session cannot be null" );
-        requireNonNull( request, "request cannot be null" );
-        session = optimizeSession( session );
-
-        boolean useSkip = ConfigUtils.getBoolean(
-                session, CONFIG_PROP_USE_SKIP_DEFAULT, CONFIG_PROP_USE_SKIP
-        );
-        if ( useSkip )
-        {
-            LOGGER.debug( "Collector skip mode enabled" );
-        }
-
-        RequestTrace trace = RequestTrace.newChild( request.getTrace(), request );
-
-        CollectResult result = new CollectResult( request );
-
-        DependencySelector depSelector = session.getDependencySelector();
-        DependencyManager depManager = session.getDependencyManager();
-        DependencyTraverser depTraverser = session.getDependencyTraverser();
-        VersionFilter verFilter = session.getVersionFilter();
-
-        Dependency root = request.getRoot();
-        List<RemoteRepository> repositories = request.getRepositories();
-        List<Dependency> dependencies = request.getDependencies();
-        List<Dependency> managedDependencies = request.getManagedDependencies();
-
-        Map<String, Object> stats = new LinkedHashMap<>();
-        long time1 = System.nanoTime();
-
-        DefaultDependencyNode node;
-        if ( root != null )
-        {
-            List<? extends Version> versions;
-            VersionRangeResult rangeResult;
-            try
-            {
-                VersionRangeRequest rangeRequest =
-                    new VersionRangeRequest( root.getArtifact(), request.getRepositories(),
-                                             request.getRequestContext() );
-                rangeRequest.setTrace( trace );
-                rangeResult = versionRangeResolver.resolveVersionRange( session, rangeRequest );
-                versions = filterVersions( root, rangeResult, verFilter, new DefaultVersionFilterContext( session ) );
-            }
-            catch ( VersionRangeResolutionException e )
-            {
-                result.addException( e );
-                throw new DependencyCollectionException( result, e.getMessage() );
-            }
-
-            Version version = versions.get( versions.size() - 1 );
-            root = root.setArtifact( root.getArtifact().setVersion( version.toString() ) );
-
-            ArtifactDescriptorResult descriptorResult;
-            try
-            {
-                ArtifactDescriptorRequest descriptorRequest = new ArtifactDescriptorRequest();
-                descriptorRequest.setArtifact( root.getArtifact() );
-                descriptorRequest.setRepositories( request.getRepositories() );
-                descriptorRequest.setRequestContext( request.getRequestContext() );
-                descriptorRequest.setTrace( trace );
-                if ( isLackingDescriptor( root.getArtifact() ) )
-                {
-                    descriptorResult = new ArtifactDescriptorResult( descriptorRequest );
-                }
-                else
-                {
-                    descriptorResult = descriptorReader.readArtifactDescriptor( session, descriptorRequest );
-                }
-            }
-            catch ( ArtifactDescriptorException e )
-            {
-                result.addException( e );
-                throw new DependencyCollectionException( result, e.getMessage() );
-            }
-
-            root = root.setArtifact( descriptorResult.getArtifact() );
-
-            if ( !session.isIgnoreArtifactDescriptorRepositories() )
-            {
-                repositories = remoteRepositoryManager.aggregateRepositories( session, repositories,
-                                                                              descriptorResult.getRepositories(),
-                                                                              true );
-            }
-            dependencies = mergeDeps( dependencies, descriptorResult.getDependencies() );
-            managedDependencies = mergeDeps( managedDependencies, descriptorResult.getManagedDependencies() );
-
-            node = new DefaultDependencyNode( root );
-            node.setRequestContext( request.getRequestContext() );
-            node.setRelocations( descriptorResult.getRelocations() );
-            node.setVersionConstraint( rangeResult.getVersionConstraint() );
-            node.setVersion( version );
-            node.setAliases( descriptorResult.getAliases() );
-            node.setRepositories( request.getRepositories() );
-        }
-        else
-        {
-            node = new DefaultDependencyNode( request.getRootArtifact() );
-            node.setRequestContext( request.getRequestContext() );
-            node.setRepositories( request.getRepositories() );
-        }
-
-        result.setRoot( node );
-
-        boolean traverse = root == null || depTraverser == null || depTraverser.traverseDependency( root );
-        String errorPath = null;
-        if ( traverse && !dependencies.isEmpty() )
-        {
-            DataPool pool = new DataPool( session );
-
-            DefaultDependencyCollectionContext context =
-                new DefaultDependencyCollectionContext( session, request.getRootArtifact(), root, managedDependencies );
-
-            DefaultVersionFilterContext versionContext = new DefaultVersionFilterContext( session );
-
-            Args args =
-                    new Args( session, trace, pool, context, versionContext, request,
-                            useSkip ? new DefaultDependencyResolutionSkipper()
-                                    : NeverDependencyResolutionSkipper.INSTANCE );
-            Results results = new Results( result, session );
-
-            DependencySelector rootDepSelector =
-                    depSelector != null ? depSelector.deriveChildSelector( context ) : null;
-            DependencyManager rootDepManager = depManager != null ? depManager.deriveChildManager( context ) : null;
-            DependencyTraverser rootDepTraverser =
-                    depTraverser != null ? depTraverser.deriveChildTraverser( context ) : null;
-            VersionFilter rootVerFilter = verFilter != null ? verFilter.deriveChildFilter( context ) : null;
-
-            List<DependencyNode> parents = Collections.singletonList( node );
-            for ( Dependency dependency : dependencies )
-            {
-                args.dependencyProcessingQueue.add(
-                        new DependencyProcessingContext( rootDepSelector, rootDepManager, rootDepTraverser,
-                                rootVerFilter, repositories, managedDependencies, parents,
-                                dependency ) );
-            }
-
-            while ( !args.dependencyProcessingQueue.isEmpty() )
-            {
-                processDependency( args, results, args.dependencyProcessingQueue.remove(), Collections.emptyList(),
-                        false );
-            }
-
-            args.skipper.report();
-            errorPath = results.errorPath;
-        }
-
-        long time2 = System.nanoTime();
-
-        DependencyGraphTransformer transformer = session.getDependencyGraphTransformer();
-        if ( transformer != null )
-        {
-            try
-            {
-                DefaultDependencyGraphTransformationContext context =
-                    new DefaultDependencyGraphTransformationContext( session );
-                context.put( TransformationContextKeys.STATS, stats );
-                result.setRoot( transformer.transformGraph( node, context ) );
-            }
-            catch ( RepositoryException e )
-            {
-                result.addException( e );
-            }
-        }
-
-        long time3 = System.nanoTime();
-        stats.put( "DefaultDependencyCollector.collectTime", time2 - time1 );
-        stats.put( "DefaultDependencyCollector.transformTime", time3 - time2 );
-        LOGGER.debug( "Dependency collection stats {}", stats );
-
-        if ( errorPath != null )
-        {
-            throw new DependencyCollectionException( result, "Failed to collect dependencies at " + errorPath );
-        }
-        if ( !result.getExceptions().isEmpty() )
-        {
-            throw new DependencyCollectionException( result );
-        }
-
-        return result;
-    }
-
-    private static RepositorySystemSession optimizeSession( RepositorySystemSession session )
-    {
-        DefaultRepositorySystemSession optimized = new DefaultRepositorySystemSession( session );
-        optimized.setArtifactTypeRegistry( CachingArtifactTypeRegistry.newInstance( session ) );
-        return optimized;
-    }
-
-    private List<Dependency> mergeDeps( List<Dependency> dominant, List<Dependency> recessive )
+            throws DependencyCollectionException
     {
-        List<Dependency> result;
-        if ( dominant == null || dominant.isEmpty() )
-        {
-            result = recessive;
-        }
-        else if ( recessive == null || recessive.isEmpty() )
+        String delegateName = ConfigUtils.getString( session, DEFAULT_COLLECTOR_IMPL, CONFIG_PROP_COLLECTOR_IMPL );
+        DependencyCollectorDelegate delegate = delegates.get( delegateName );
+        if ( delegate == null )
         {
-            result = dominant;
+            throw new IllegalArgumentException( "Unknown collector impl: '" + delegateName
+                    + "', known implementations are " + delegates.keySet() );
         }
-        else
-        {
-            int initialCapacity = dominant.size() + recessive.size();
-            result = new ArrayList<>( initialCapacity );
-            Collection<String> ids = new HashSet<>( initialCapacity, 1.0f );
-            for ( Dependency dependency : dominant )
-            {
-                ids.add( getId( dependency.getArtifact() ) );
-                result.add( dependency );
-            }
-            for ( Dependency dependency : recessive )
-            {
-                if ( !ids.contains( getId( dependency.getArtifact() ) ) )
-                {
-                    result.add( dependency );
-                }
-            }
-        }
-        return result;
-    }
-
-    private static String getId( Artifact a )
-    {
-        return a.getGroupId() + ':' + a.getArtifactId() + ':' + a.getClassifier() + ':' + a.getExtension();
+        return delegate.collectDependencies( session, request );
     }
-
-    @SuppressWarnings( "checkstyle:parameternumber" )
-    private void processDependency( Args args, Results results, DependencyProcessingContext context,
-                                    List<Artifact> relocations, boolean disableVersionManagement )
-    {
-
-        if ( context.depSelector != null && !context.depSelector.selectDependency( context.dependency ) )
-        {
-            return;
-        }
-
-        PremanagedDependency preManaged =
-                PremanagedDependency.create( context.depManager, context.dependency, disableVersionManagement,
-                        args.premanagedState );
-        Dependency dependency = preManaged.managedDependency;
-
-        boolean noDescriptor = isLackingDescriptor( dependency.getArtifact() );
-
-        boolean traverse =
-                !noDescriptor && ( context.depTraverser == null || context.depTraverser.traverseDependency(
-                        dependency ) );
-
-        List<? extends Version> versions;
-        VersionRangeResult rangeResult;
-        try
-        {
-            VersionRangeRequest rangeRequest = createVersionRangeRequest( args, context.repositories, dependency );
-
-            rangeResult = cachedResolveRangeResult( rangeRequest, args.pool, args.session );
-
-            versions = filterVersions( dependency, rangeResult, context.verFilter, args.versionContext );
-        }
-        catch ( VersionRangeResolutionException e )
-        {
-            results.addException( dependency, e, context.parents );
-            return;
-        }
-
-        //Resolve newer version first to maximize benefits of skipper
-        Collections.reverse( versions );
-        for ( Version version : versions )
-        {
-            Artifact originalArtifact = dependency.getArtifact().setVersion( version.toString() );
-            Dependency d = dependency.setArtifact( originalArtifact );
-
-            ArtifactDescriptorRequest descriptorRequest =
-                    createArtifactDescriptorRequest( args, context.repositories, d );
-
-            final ArtifactDescriptorResult descriptorResult =
-                    noDescriptor
-                            ? new ArtifactDescriptorResult( descriptorRequest )
-                            : resolveCachedArtifactDescriptor( args.pool, descriptorRequest, args.session,
-                                    context.withDependency( d ), results );
-
-            if ( descriptorResult != null )
-            {
-                d = d.setArtifact( descriptorResult.getArtifact() );
-
-                int cycleEntry = find( context.parents, d.getArtifact() );
-                if ( cycleEntry >= 0 )
-                {
-                    results.addCycle( context.parents, cycleEntry, d );
-                    DependencyNode cycleNode = context.parents.get( cycleEntry );
-                    if ( cycleNode.getDependency() != null )
-                    {
-                        DefaultDependencyNode child =
-                                createDependencyNode( relocations, preManaged, rangeResult, version, d,
-                                        descriptorResult, cycleNode );
-                        context.getParent().getChildren().add( child );
-                        continue;
-                    }
-                }
-
-                if ( !descriptorResult.getRelocations().isEmpty() )
-                {
-                    boolean disableVersionManagementSubsequently =
-                        originalArtifact.getGroupId().equals( d.getArtifact().getGroupId() )
-                            && originalArtifact.getArtifactId().equals( d.getArtifact().getArtifactId() );
-
-                    processDependency( args, results, context.withDependency( d ), descriptorResult.getRelocations(),
-                            disableVersionManagementSubsequently );
-                    return;
-                }
-                else
-                {
-                    d = args.pool.intern( d.setArtifact( args.pool.intern( d.getArtifact() ) ) );
-
-                    List<RemoteRepository> repos =
-                        getRemoteRepositories( rangeResult.getRepository( version ), context.repositories );
-
-                    DefaultDependencyNode child =
-                        createDependencyNode( relocations, preManaged, rangeResult, version, d,
-                                              descriptorResult.getAliases(), repos, args.request.getRequestContext() );
-
-                    context.getParent().getChildren().add( child );
-
-                    boolean recurse = traverse && !descriptorResult.getDependencies().isEmpty();
-                    if ( recurse )
-                    {
-                        doRecurse( args, context.withDependency( d ), descriptorResult, child );
-                    }
-                }
-            }
-            else
-            {
-                List<RemoteRepository> repos =
-                    getRemoteRepositories( rangeResult.getRepository( version ), context.repositories );
-                DefaultDependencyNode child =
-                    createDependencyNode( relocations, preManaged, rangeResult, version, d, null, repos,
-                                          args.request.getRequestContext() );
-                context.getParent().getChildren().add( child );
-            }
-        }
-    }
-
-    @SuppressWarnings( "checkstyle:parameternumber" )
-    private void doRecurse( Args args, DependencyProcessingContext parentContext,
-                            ArtifactDescriptorResult descriptorResult, DefaultDependencyNode child )
-    {
-        DefaultDependencyCollectionContext context = args.collectionContext;
-        context.set( parentContext.dependency, descriptorResult.getManagedDependencies() );
-
-        DependencySelector childSelector =
-                parentContext.depSelector != null ? parentContext.depSelector.deriveChildSelector( context ) : null;
-        DependencyManager childManager =
-                parentContext.depManager != null ? parentContext.depManager.deriveChildManager( context ) : null;
-        DependencyTraverser childTraverser =
-                parentContext.depTraverser != null ? parentContext.depTraverser.deriveChildTraverser( context ) : null;
-        VersionFilter childFilter =
-                parentContext.verFilter != null ? parentContext.verFilter.deriveChildFilter( context ) : null;
-
-        final List<RemoteRepository> childRepos =
-                args.ignoreRepos
-                        ? parentContext.repositories
-                        : remoteRepositoryManager.aggregateRepositories( args.session, parentContext.repositories,
-                        descriptorResult.getRepositories(), true );
-
-        Object key =
-                args.pool.toKey( parentContext.dependency.getArtifact(), childRepos, childSelector, childManager,
-                        childTraverser, childFilter );
-
-        List<DependencyNode> children = args.pool.getChildren( key );
-        if ( children == null )
-        {
-            boolean skipResolution = args.skipper.skipResolution( child, parentContext.parents );
-            if ( !skipResolution )
-            {
-                List<DependencyNode> parents = new ArrayList<>( parentContext.parents.size() + 1 );
-                parents.addAll( parentContext.parents );
-                parents.add( child );
-                for ( Dependency dependency : descriptorResult.getDependencies() )
-                {
-                    args.dependencyProcessingQueue.add(
-                            new DependencyProcessingContext( childSelector, childManager, childTraverser, childFilter,
-                                    childRepos, descriptorResult.getManagedDependencies(), parents, dependency ) );
-                }
-                args.pool.putChildren( key, child.getChildren() );
-                args.skipper.cache( child, parents );
-            }
-        }
-        else
-        {
-            child.setChildren( children );
-        }
-    }
-
-    private ArtifactDescriptorResult resolveCachedArtifactDescriptor( DataPool pool,
-                                                                      ArtifactDescriptorRequest descriptorRequest,
-                                                                      RepositorySystemSession session,
-                                                                      DependencyProcessingContext context,
-                                                                      Results results )
-    {
-        Object key = pool.toKey( descriptorRequest );
-        ArtifactDescriptorResult descriptorResult = pool.getDescriptor( key, descriptorRequest );
-        if ( descriptorResult == null )
-        {
-            try
-            {
-                descriptorResult = descriptorReader.readArtifactDescriptor( session, descriptorRequest );
-                pool.putDescriptor( key, descriptorResult );
-            }
-            catch ( ArtifactDescriptorException e )
-            {
-                results.addException( context.dependency, e, context.parents );
-                pool.putDescriptor( key, e );
-                return null;
-            }
-
-        }
-        else if ( descriptorResult == DataPool.NO_DESCRIPTOR )
-        {
-            return null;
-        }
-
-        return descriptorResult;
-    }
-
-    @SuppressWarnings( "checkstyle:parameternumber" )
-    private static DefaultDependencyNode createDependencyNode( List<Artifact> relocations,
-                                                               PremanagedDependency preManaged,
-                                                               VersionRangeResult rangeResult, Version version,
-                                                               Dependency d, Collection<Artifact> aliases,
-                                                               List<RemoteRepository> repos, String requestContext )
-    {
-        DefaultDependencyNode child = new DefaultDependencyNode( d );
-        preManaged.applyTo( child );
-        child.setRelocations( relocations );
-        child.setVersionConstraint( rangeResult.getVersionConstraint() );
-        child.setVersion( version );
-        child.setAliases( aliases );
-        child.setRepositories( repos );
-        child.setRequestContext( requestContext );
-        return child;
-    }
-
-    private static DefaultDependencyNode createDependencyNode( List<Artifact> relocations,
-                                                               PremanagedDependency preManaged,
-                                                               VersionRangeResult rangeResult, Version version,
-                                                               Dependency d, ArtifactDescriptorResult descriptorResult,
-                                                               DependencyNode cycleNode )
-    {
-        DefaultDependencyNode child =
-            createDependencyNode( relocations, preManaged, rangeResult, version, d, descriptorResult.getAliases(),
-                                  cycleNode.getRepositories(), cycleNode.getRequestContext() );
-        child.setChildren( cycleNode.getChildren() );
-        return child;
-    }
-
-    private static ArtifactDescriptorRequest createArtifactDescriptorRequest( Args args,
-                                                                              List<RemoteRepository> repositories,
-                                                                              Dependency d )
-    {
-        ArtifactDescriptorRequest descriptorRequest = new ArtifactDescriptorRequest();
-        descriptorRequest.setArtifact( d.getArtifact() );
-        descriptorRequest.setRepositories( repositories );
-        descriptorRequest.setRequestContext( args.request.getRequestContext() );
-        descriptorRequest.setTrace( args.trace );
-        return descriptorRequest;
-    }
-
-    private static VersionRangeRequest createVersionRangeRequest( Args args, List<RemoteRepository> repositories,
-                                                                  Dependency dependency )
-    {
-        VersionRangeRequest rangeRequest = new VersionRangeRequest();
-        rangeRequest.setArtifact( dependency.getArtifact() );
-        rangeRequest.setRepositories( repositories );
-        rangeRequest.setRequestContext( args.request.getRequestContext() );
-        rangeRequest.setTrace( args.trace );
-        return rangeRequest;
-    }
-
-    private VersionRangeResult cachedResolveRangeResult( VersionRangeRequest rangeRequest, DataPool pool,
-                                                         RepositorySystemSession session )
-        throws VersionRangeResolutionException
-    {
-        Object key = pool.toKey( rangeRequest );
-        VersionRangeResult rangeResult = pool.getConstraint( key, rangeRequest );
-        if ( rangeResult == null )
-        {
-            rangeResult = versionRangeResolver.resolveVersionRange( session, rangeRequest );
-            pool.putConstraint( key, rangeResult );
-        }
-        return rangeResult;
-    }
-
-    private static boolean isLackingDescriptor( Artifact artifact )
-    {
-        return artifact.getProperty( ArtifactProperties.LOCAL_PATH, null ) != null;
-    }
-
-    private static List<RemoteRepository> getRemoteRepositories( ArtifactRepository repository,
-                                                                 List<RemoteRepository> repositories )
-    {
-        if ( repository instanceof RemoteRepository )
-        {
-            return Collections.singletonList( (RemoteRepository) repository );
-        }
-        if ( repository != null )
-        {
-            return Collections.emptyList();
-        }
-        return repositories;
-    }
-
-    private static List<? extends Version> filterVersions( Dependency dependency, VersionRangeResult rangeResult,
-                                                           VersionFilter verFilter,
-                                                           DefaultVersionFilterContext verContext )
-        throws VersionRangeResolutionException
-    {
-        if ( rangeResult.getVersions().isEmpty() )
-        {
-            throw new VersionRangeResolutionException( rangeResult,
-                                                       "No versions available for " + dependency.getArtifact()
-                                                           + " within specified range" );
-        }
-
-        List<? extends Version> versions;
-        if ( verFilter != null && rangeResult.getVersionConstraint().getRange() != null )
-        {
-            verContext.set( dependency, rangeResult );
-            try
-            {
-                verFilter.filterVersions( verContext );
-            }
-            catch ( RepositoryException e )
-            {
-                throw new VersionRangeResolutionException( rangeResult,
-                                                           "Failed to filter versions for " + dependency.getArtifact()
-                                                               + ": " + e.getMessage(), e );
-            }
-            versions = verContext.get();
-            if ( versions.isEmpty() )
-            {
-                throw new VersionRangeResolutionException( rangeResult,
-                                                           "No acceptable versions for " + dependency.getArtifact()
-                                                               + ": " + rangeResult.getVersions() );
-            }
-        }
-        else
-        {
-            versions = rangeResult.getVersions();
-        }
-        return versions;
-    }
-
-    static class Args
-    {
-
-        final RepositorySystemSession session;
-
-        final boolean ignoreRepos;
-
-        final boolean premanagedState;
-
-        final RequestTrace trace;
-
-        final DataPool pool;
-
-        final Queue<DependencyProcessingContext> dependencyProcessingQueue = new ArrayDeque<>( 128 );
-
-        final DefaultDependencyCollectionContext collectionContext;
-
-        final DefaultVersionFilterContext versionContext;
-
-        final CollectRequest request;
-
-        final DependencyResolutionSkipper skipper;
-
-        Args( RepositorySystemSession session, RequestTrace trace, DataPool pool,
-                     DefaultDependencyCollectionContext collectionContext, DefaultVersionFilterContext versionContext,
-                     CollectRequest request, DependencyResolutionSkipper skipper )
-        {
-            this.session = session;
-            this.request = request;
-            this.ignoreRepos = session.isIgnoreArtifactDescriptorRepositories();
-            this.premanagedState = ConfigUtils.getBoolean( session, false, DependencyManagerUtils.CONFIG_PROP_VERBOSE );
-            this.trace = trace;
-            this.pool = pool;
-            this.collectionContext = collectionContext;
-            this.versionContext = versionContext;
-            this.skipper = skipper;
-        }
-
-    }
-
-    static class Results
-    {
-
-        private final CollectResult result;
-
-        final int maxExceptions;
-
-        final int maxCycles;
-
-        String errorPath;
-
-        Results( CollectResult result, RepositorySystemSession session )
-        {
-            this.result = result;
-
-            maxExceptions =
-                    ConfigUtils.getInteger( session, CONFIG_PROP_MAX_EXCEPTIONS_DEFAULT, CONFIG_PROP_MAX_EXCEPTIONS );
-
-            maxCycles = ConfigUtils.getInteger( session, CONFIG_PROP_MAX_CYCLES_DEFAULT, CONFIG_PROP_MAX_CYCLES );
-        }
-
-        public void addException( Dependency dependency, Exception e, List<DependencyNode> nodes )
-        {
-            if ( maxExceptions < 0 || result.getExceptions().size() < maxExceptions )
-            {
-                result.addException( e );
-                if ( errorPath == null )
-                {
-                    StringBuilder buffer = new StringBuilder( 256 );
-                    for ( DependencyNode node : nodes )
-                    {
-                        if ( buffer.length() > 0 )
-                        {
-                            buffer.append( " -> " );
-                        }
-                        Dependency dep = node.getDependency();
-                        if ( dep != null )
-                        {
-                            buffer.append( dep.getArtifact() );
-                        }
-                    }
-                    if ( buffer.length() > 0 )
-                    {
-                        buffer.append( " -> " );
-                    }
-                    buffer.append( dependency.getArtifact() );
-                    errorPath = buffer.toString();
-                }
-            }
-        }
-
-        public void addCycle( List<DependencyNode> nodes, int cycleEntry, Dependency dependency )
-        {
-            if ( maxCycles < 0 || result.getCycles().size() < maxCycles )
-            {
-                result.addCycle( new DefaultDependencyCycle( nodes, cycleEntry, dependency ) );
-            }
-        }
-
-    }
-
-    static class PremanagedDependency
-    {
-
-        final String premanagedVersion;
-
-        final String premanagedScope;
-
-        final Boolean premanagedOptional;
-
-        /**
-         * @since 1.1.0
-         */
-        final Collection<Exclusion> premanagedExclusions;
-
-        /**
-         * @since 1.1.0
-         */
-        final Map<String, String> premanagedProperties;
-
-        final int managedBits;
-
-        final Dependency managedDependency;
-
-        final boolean premanagedState;
-
-        @SuppressWarnings( "checkstyle:parameternumber" )
-        PremanagedDependency( String premanagedVersion, String premanagedScope, Boolean premanagedOptional,
-                              Collection<Exclusion> premanagedExclusions, Map<String, String> premanagedProperties,
-                              int managedBits, Dependency managedDependency, boolean premanagedState )
-        {
-            this.premanagedVersion = premanagedVersion;
-            this.premanagedScope = premanagedScope;
-            this.premanagedOptional = premanagedOptional;
-            this.premanagedExclusions =
-                premanagedExclusions != null
-                    ? Collections.unmodifiableCollection( new ArrayList<>( premanagedExclusions ) )
-                    : null;
-
-            this.premanagedProperties =
-                premanagedProperties != null
-                    ? Collections.unmodifiableMap( new HashMap<>( premanagedProperties ) )
-                    : null;
-
-            this.managedBits = managedBits;
-            this.managedDependency = managedDependency;
-            this.premanagedState = premanagedState;
-        }
-
-        static PremanagedDependency create( DependencyManager depManager, Dependency dependency,
-                                            boolean disableVersionManagement, boolean premanagedState )
-        {
-            DependencyManagement depMngt = depManager != null ? depManager.manageDependency( dependency ) : null;
-
-            int managedBits = 0;
-            String premanagedVersion = null;
-            String premanagedScope = null;
-            Boolean premanagedOptional = null;
-            Collection<Exclusion> premanagedExclusions = null;
-            Map<String, String> premanagedProperties = null;
-
-            if ( depMngt != null )
-            {
-                if ( depMngt.getVersion() != null && !disableVersionManagement )
-                {
-                    Artifact artifact = dependency.getArtifact();
-                    premanagedVersion = artifact.getVersion();
-                    dependency = dependency.setArtifact( artifact.setVersion( depMngt.getVersion() ) );
-                    managedBits |= DependencyNode.MANAGED_VERSION;
-                }
-                if ( depMngt.getProperties() != null )
-                {
-                    Artifact artifact = dependency.getArtifact();
-                    premanagedProperties = artifact.getProperties();
-                    dependency = dependency.setArtifact( artifact.setProperties( depMngt.getProperties() ) );
-                    managedBits |= DependencyNode.MANAGED_PROPERTIES;
-                }
-                if ( depMngt.getScope() != null )
-                {
-                    premanagedScope = dependency.getScope();
-                    dependency = dependency.setScope( depMngt.getScope() );
-                    managedBits |= DependencyNode.MANAGED_SCOPE;
-                }
-                if ( depMngt.getOptional() != null )
-                {
-                    premanagedOptional = dependency.isOptional();
-                    dependency = dependency.setOptional( depMngt.getOptional() );
-                    managedBits |= DependencyNode.MANAGED_OPTIONAL;
-                }
-                if ( depMngt.getExclusions() != null )
-                {
-                    premanagedExclusions = dependency.getExclusions();
-                    dependency = dependency.setExclusions( depMngt.getExclusions() );
-                    managedBits |= DependencyNode.MANAGED_EXCLUSIONS;
-                }
-            }
-            return new PremanagedDependency( premanagedVersion, premanagedScope, premanagedOptional,
-                                             premanagedExclusions, premanagedProperties, managedBits, dependency,
-                                             premanagedState );
-
-        }
-
-        public void applyTo( DefaultDependencyNode child )
-        {
-            child.setManagedBits( managedBits );
-            if ( premanagedState )
-            {
-                child.setData( DependencyManagerUtils.NODE_DATA_PREMANAGED_VERSION, premanagedVersion );
-                child.setData( DependencyManagerUtils.NODE_DATA_PREMANAGED_SCOPE, premanagedScope );
-                child.setData( DependencyManagerUtils.NODE_DATA_PREMANAGED_OPTIONAL, premanagedOptional );
-                child.setData( DependencyManagerUtils.NODE_DATA_PREMANAGED_EXCLUSIONS, premanagedExclusions );
-                child.setData( DependencyManagerUtils.NODE_DATA_PREMANAGED_PROPERTIES, premanagedProperties );
-            }
-        }
-
-    }
-
 }
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyGraphTransformationContext.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyGraphTransformationContext.java
index 41c01269..28ea7472 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyGraphTransformationContext.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyGraphTransformationContext.java
@@ -28,7 +28,7 @@ import org.eclipse.aether.collection.DependencyGraphTransformationContext;
 
 /**
  */
-class DefaultDependencyGraphTransformationContext
+public class DefaultDependencyGraphTransformationContext
     implements DependencyGraphTransformationContext
 {
 
@@ -36,7 +36,7 @@ class DefaultDependencyGraphTransformationContext
 
     private final Map<Object, Object> map;
 
-    DefaultDependencyGraphTransformationContext( RepositorySystemSession session )
+    public DefaultDependencyGraphTransformationContext( RepositorySystemSession session )
     {
         this.session = session;
         this.map = new HashMap<>();
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultVersionFilterContext.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultVersionFilterContext.java
index bfea0626..55b6fba4 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultVersionFilterContext.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultVersionFilterContext.java
@@ -36,7 +36,7 @@ import org.eclipse.aether.version.VersionConstraint;
 /**
  * @see DefaultDependencyCollector
  */
-final class DefaultVersionFilterContext
+public final class DefaultVersionFilterContext
     implements VersionFilter.VersionFilterContext
 {
     private final RepositorySystemSession session;
@@ -47,7 +47,7 @@ final class DefaultVersionFilterContext
 
     private List<Version> versions;
 
-    DefaultVersionFilterContext( RepositorySystemSession session )
+    public DefaultVersionFilterContext( RepositorySystemSession session )
     {
         this.session = session;
     }
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/NeverDependencyResolutionSkipper.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DependencyCollectorDelegate.java
similarity index 57%
copy from maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/NeverDependencyResolutionSkipper.java
copy to maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DependencyCollectorDelegate.java
index acd6636f..5d17efc6 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/NeverDependencyResolutionSkipper.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DependencyCollectorDelegate.java
@@ -19,33 +19,13 @@ package org.eclipse.aether.internal.impl.collect;
  * under the License.
  */
 
-import org.eclipse.aether.graph.DependencyNode;
-import org.eclipse.aether.impl.DependencyResolutionSkipper;
-
-import java.util.List;
+import org.eclipse.aether.impl.DependencyCollector;
 
 /**
- * Skipper for Non-skip approach.
+ * The delegate to the actual implementation.
+ *
+ * @since 1.8.0
  */
-final class NeverDependencyResolutionSkipper implements DependencyResolutionSkipper
+public interface DependencyCollectorDelegate extends DependencyCollector
 {
-    static final DependencyResolutionSkipper INSTANCE = new NeverDependencyResolutionSkipper();
-
-    @Override
-    public boolean skipResolution( DependencyNode node, List<DependencyNode> parents )
-    {
-        return false;
-    }
-
-    @Override
-    public void cache( DependencyNode node, List<DependencyNode> parents )
-    {
-
-    }
-
-    @Override
-    public void report()
-    {
-
-    }
 }
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollector.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollector.java
similarity index 95%
copy from maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollector.java
copy to maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollector.java
index a895bb9b..4836d635 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollector.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollector.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -19,6 +19,10 @@ package org.eclipse.aether.internal.impl.collect;
  * under the License.
  */
 
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Singleton;
+
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -30,13 +34,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.Queue;
 
-import static java.util.Objects.requireNonNull;
-import static org.eclipse.aether.internal.impl.collect.DefaultDependencyCycle.find;
-
-import javax.inject.Inject;
-import javax.inject.Named;
-import javax.inject.Singleton;
-
 import org.eclipse.aether.DefaultRepositorySystemSession;
 import org.eclipse.aether.RepositoryException;
 import org.eclipse.aether.RepositorySystemSession;
@@ -57,10 +54,15 @@ import org.eclipse.aether.graph.Dependency;
 import org.eclipse.aether.graph.DependencyNode;
 import org.eclipse.aether.graph.Exclusion;
 import org.eclipse.aether.impl.ArtifactDescriptorReader;
-import org.eclipse.aether.impl.DependencyCollector;
 import org.eclipse.aether.impl.DependencyResolutionSkipper;
 import org.eclipse.aether.impl.RemoteRepositoryManager;
 import org.eclipse.aether.impl.VersionRangeResolver;
+import org.eclipse.aether.internal.impl.collect.CachingArtifactTypeRegistry;
+import org.eclipse.aether.internal.impl.collect.DataPool;
+import org.eclipse.aether.internal.impl.collect.DefaultDependencyCollectionContext;
+import org.eclipse.aether.internal.impl.collect.DefaultDependencyGraphTransformationContext;
+import org.eclipse.aether.internal.impl.collect.DefaultVersionFilterContext;
+import org.eclipse.aether.internal.impl.collect.DependencyCollectorDelegate;
 import org.eclipse.aether.repository.ArtifactRepository;
 import org.eclipse.aether.repository.RemoteRepository;
 import org.eclipse.aether.resolution.ArtifactDescriptorException;
@@ -78,16 +80,20 @@ import org.eclipse.aether.version.Version;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import static java.util.Objects.requireNonNull;
+import static org.eclipse.aether.internal.impl.collect.bf.BfDependencyCycle.find;
+
 /**
  */
 @Singleton
-@Named
-public class DefaultDependencyCollector
-    implements DependencyCollector, Service
+@Named( BfDependencyCollector.NAME )
+public class BfDependencyCollector
+        implements DependencyCollectorDelegate, Service
 {
+    public static final String NAME = "bf";
 
     /**
-     * The key in the repository session's {@link org.eclipse.aether.RepositorySystemSession#getConfigProperties()
+     * The key in the repository session's {@link RepositorySystemSession#getConfigProperties()
      * configuration properties} used to store a {@link Boolean} flag controlling the resolver's skip mode.
      *
      * @since 1.8.0
@@ -109,7 +115,7 @@ public class DefaultDependencyCollector
 
     private static final int CONFIG_PROP_MAX_CYCLES_DEFAULT = 10;
 
-    private static final Logger LOGGER = LoggerFactory.getLogger( DefaultDependencyCollector.class );
+    private static final Logger LOGGER = LoggerFactory.getLogger( BfDependencyCollector.class );
 
     private RemoteRepositoryManager remoteRepositoryManager;
 
@@ -117,15 +123,15 @@ public class DefaultDependencyCollector
 
     private VersionRangeResolver versionRangeResolver;
 
-    public DefaultDependencyCollector()
+    public BfDependencyCollector()
     {
         // enables default constructor
     }
 
     @Inject
-    DefaultDependencyCollector( RemoteRepositoryManager remoteRepositoryManager,
-                                ArtifactDescriptorReader artifactDescriptorReader,
-                                VersionRangeResolver versionRangeResolver )
+    BfDependencyCollector( RemoteRepositoryManager remoteRepositoryManager,
+                           ArtifactDescriptorReader artifactDescriptorReader,
+                           VersionRangeResolver versionRangeResolver )
     {
         setRemoteRepositoryManager( remoteRepositoryManager );
         setArtifactDescriptorReader( artifactDescriptorReader );
@@ -139,20 +145,20 @@ public class DefaultDependencyCollector
         setVersionRangeResolver( locator.getService( VersionRangeResolver.class ) );
     }
 
-    public DefaultDependencyCollector setRemoteRepositoryManager( RemoteRepositoryManager remoteRepositoryManager )
+    public BfDependencyCollector setRemoteRepositoryManager( RemoteRepositoryManager remoteRepositoryManager )
     {
         this.remoteRepositoryManager =
                 requireNonNull( remoteRepositoryManager, "remote repository provider cannot be null" );
         return this;
     }
 
-    public DefaultDependencyCollector setArtifactDescriptorReader( ArtifactDescriptorReader artifactDescriptorReader )
+    public BfDependencyCollector setArtifactDescriptorReader( ArtifactDescriptorReader artifactDescriptorReader )
     {
         descriptorReader = requireNonNull( artifactDescriptorReader, "artifact descriptor reader cannot be null" );
         return this;
     }
 
-    public DefaultDependencyCollector setVersionRangeResolver( VersionRangeResolver versionRangeResolver )
+    public BfDependencyCollector setVersionRangeResolver( VersionRangeResolver versionRangeResolver )
     {
         this.versionRangeResolver =
                 requireNonNull( versionRangeResolver, "version range resolver cannot be null" );
@@ -294,7 +300,7 @@ public class DefaultDependencyCollector
             for ( Dependency dependency : dependencies )
             {
                 args.dependencyProcessingQueue.add(
-                        new DependencyProcessingContext( rootDepSelector, rootDepManager, rootDepTraverser,
+                        new BfProcessingContext( rootDepSelector, rootDepManager, rootDepTraverser,
                                 rootVerFilter, repositories, managedDependencies, parents,
                                 dependency ) );
             }
@@ -389,7 +395,7 @@ public class DefaultDependencyCollector
     }
 
     @SuppressWarnings( "checkstyle:parameternumber" )
-    private void processDependency( Args args, Results results, DependencyProcessingContext context,
+    private void processDependency( Args args, Results results, BfProcessingContext context,
                                     List<Artifact> relocations, boolean disableVersionManagement )
     {
 
@@ -503,7 +509,7 @@ public class DefaultDependencyCollector
     }
 
     @SuppressWarnings( "checkstyle:parameternumber" )
-    private void doRecurse( Args args, DependencyProcessingContext parentContext,
+    private void doRecurse( Args args, BfProcessingContext parentContext,
                             ArtifactDescriptorResult descriptorResult, DefaultDependencyNode child )
     {
         DefaultDependencyCollectionContext context = args.collectionContext;
@@ -540,7 +546,7 @@ public class DefaultDependencyCollector
                 for ( Dependency dependency : descriptorResult.getDependencies() )
                 {
                     args.dependencyProcessingQueue.add(
-                            new DependencyProcessingContext( childSelector, childManager, childTraverser, childFilter,
+                            new BfProcessingContext( childSelector, childManager, childTraverser, childFilter,
                                     childRepos, descriptorResult.getManagedDependencies(), parents, dependency ) );
                 }
                 args.pool.putChildren( key, child.getChildren() );
@@ -556,7 +562,7 @@ public class DefaultDependencyCollector
     private ArtifactDescriptorResult resolveCachedArtifactDescriptor( DataPool pool,
                                                                       ArtifactDescriptorRequest descriptorRequest,
                                                                       RepositorySystemSession session,
-                                                                      DependencyProcessingContext context,
+                                                                      BfProcessingContext context,
                                                                       Results results )
     {
         Object key = pool.toKey( descriptorRequest );
@@ -725,7 +731,7 @@ public class DefaultDependencyCollector
 
         final DataPool pool;
 
-        final Queue<DependencyProcessingContext> dependencyProcessingQueue = new ArrayDeque<>( 128 );
+        final Queue<BfProcessingContext> dependencyProcessingQueue = new ArrayDeque<>( 128 );
 
         final DefaultDependencyCollectionContext collectionContext;
 
@@ -807,7 +813,7 @@ public class DefaultDependencyCollector
         {
             if ( maxCycles < 0 || result.getCycles().size() < maxCycles )
             {
-                result.addCycle( new DefaultDependencyCycle( nodes, cycleEntry, dependency ) );
+                result.addCycle( new BfDependencyCycle( nodes, cycleEntry, dependency ) );
             }
         }
 
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCycle.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCycle.java
similarity index 95%
rename from maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCycle.java
rename to maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCycle.java
index dd1565c9..94a566d4 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCycle.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCycle.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -27,12 +27,13 @@ import org.eclipse.aether.artifact.Artifact;
 import org.eclipse.aether.graph.Dependency;
 import org.eclipse.aether.graph.DependencyCycle;
 import org.eclipse.aether.graph.DependencyNode;
+import org.eclipse.aether.internal.impl.collect.DefaultDependencyCollector;
 import org.eclipse.aether.util.artifact.ArtifactIdUtils;
 
 /**
  * @see DefaultDependencyCollector
  */
-final class DefaultDependencyCycle
+final class BfDependencyCycle
     implements DependencyCycle
 {
 
@@ -40,7 +41,7 @@ final class DefaultDependencyCycle
 
     private final int cycleEntry;
 
-    DefaultDependencyCycle( List<DependencyNode> nodes, int cycleEntry, Dependency dependency )
+    BfDependencyCycle( List<DependencyNode> nodes, int cycleEntry, Dependency dependency )
     {
         // skip root node unless it actually has a dependency or is considered the cycle entry (due to its label)
         int offset = ( cycleEntry > 0 && nodes.get( 0 ).getDependency() == null ) ? 1 : 0;
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DependencyProcessingContext.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfProcessingContext.java
similarity index 76%
rename from maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DependencyProcessingContext.java
rename to maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfProcessingContext.java
index 9820ad07..f18376f2 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DependencyProcessingContext.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfProcessingContext.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -29,7 +29,7 @@ import org.eclipse.aether.graph.Dependency;
 import org.eclipse.aether.graph.DependencyNode;
 import org.eclipse.aether.repository.RemoteRepository;
 
-final class DependencyProcessingContext
+final class BfProcessingContext
 {
     final DependencySelector depSelector;
     final DependencyManager depManager;
@@ -45,14 +45,14 @@ final class DependencyProcessingContext
     Dependency dependency;
 
     @SuppressWarnings( "checkstyle:parameternumber" )
-    DependencyProcessingContext( DependencySelector depSelector,
-                                 DependencyManager depManager,
-                                 DependencyTraverser depTraverser,
-                                 VersionFilter verFilter,
-                                 List<RemoteRepository> repositories,
-                                 List<Dependency> managedDependencies,
-                                 List<DependencyNode> parents,
-                                 Dependency dependency )
+    BfProcessingContext( DependencySelector depSelector,
+                         DependencyManager depManager,
+                         DependencyTraverser depTraverser,
+                         VersionFilter verFilter,
+                         List<RemoteRepository> repositories,
+                         List<Dependency> managedDependencies,
+                         List<DependencyNode> parents,
+                         Dependency dependency )
     {
         this.depSelector = depSelector;
         this.depManager = depManager;
@@ -64,7 +64,7 @@ final class DependencyProcessingContext
         this.parents = parents;
     }
 
-    DependencyProcessingContext withDependency( Dependency dependency )
+    BfProcessingContext withDependency( Dependency dependency )
     {
         this.dependency = dependency;
         return this;
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyResolutionSkipper.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/DefaultDependencyResolutionSkipper.java
similarity index 95%
rename from maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyResolutionSkipper.java
rename to maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/DefaultDependencyResolutionSkipper.java
index 408b0e16..38fcd4e7 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyResolutionSkipper.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/DefaultDependencyResolutionSkipper.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -32,18 +32,18 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
 
-final class DefaultDependencyResolutionSkipper implements DependencyResolutionSkipper
+/**
+ * Skipper for Skip-and-reconcile approach.
+ *
+ * @see BfDependencyCollector
+ */
+public final class DefaultDependencyResolutionSkipper implements DependencyResolutionSkipper
 {
     private static final Logger LOGGER = LoggerFactory.getLogger( DefaultDependencyResolutionSkipper.class );
 
-    private Map<DependencyNode, DependencyResolutionResult> results = new LinkedHashMap<>( 256 );
-    private CacheManager cacheManager = new CacheManager();
-    private CoordinateManager coordinateManager = new CoordinateManager();
-
-    DefaultDependencyResolutionSkipper()
-    {
-        // enables default constructor
-    }
+    private final Map<DependencyNode, DependencyResolutionResult> results = new LinkedHashMap<>( 256 );
+    private final CacheManager cacheManager = new CacheManager();
+    private final CoordinateManager coordinateManager = new CoordinateManager();
 
     @Override
     public boolean skipResolution( DependencyNode node, List<DependencyNode> parents )
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/NeverDependencyResolutionSkipper.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/NeverDependencyResolutionSkipper.java
similarity index 82%
rename from maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/NeverDependencyResolutionSkipper.java
rename to maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/NeverDependencyResolutionSkipper.java
index acd6636f..8ad4450d 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/NeverDependencyResolutionSkipper.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/NeverDependencyResolutionSkipper.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -26,10 +26,12 @@ import java.util.List;
 
 /**
  * Skipper for Non-skip approach.
+ *
+ * @see BfDependencyCollector
  */
-final class NeverDependencyResolutionSkipper implements DependencyResolutionSkipper
+public final class NeverDependencyResolutionSkipper implements DependencyResolutionSkipper
 {
-    static final DependencyResolutionSkipper INSTANCE = new NeverDependencyResolutionSkipper();
+    public static final DependencyResolutionSkipper INSTANCE = new NeverDependencyResolutionSkipper();
 
     @Override
     public boolean skipResolution( DependencyNode node, List<DependencyNode> parents )
diff --git a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectorTest.java b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollectorTest.java
similarity index 98%
rename from maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectorTest.java
rename to maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollectorTest.java
index 7d034bdd..3c4ea005 100644
--- a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectorTest.java
+++ b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollectorTest.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -18,14 +18,6 @@ package org.eclipse.aether.internal.impl.collect;
  * specific language governing permissions and limitations
  * under the License.
  */
-import static java.util.Objects.requireNonNull;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -73,12 +65,21 @@ import org.eclipse.aether.util.graph.version.HighestVersionFilter;
 import org.junit.Before;
 import org.junit.Test;
 
+import static java.util.Objects.requireNonNull;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
 /**
  */
-public class DefaultDependencyCollectorTest
+public class BfDependencyCollectorTest
 {
 
-    protected DefaultDependencyCollector collector;
+    protected BfDependencyCollector collector;
 
     protected DefaultRepositorySystemSession session;
 
@@ -110,9 +111,9 @@ public class DefaultDependencyCollectorTest
     public void setupCollector( boolean useSkip )
     {
         session = TestUtils.newSession();
-        session.setConfigProperty( DefaultDependencyCollector.CONFIG_PROP_USE_SKIP, useSkip );
+        session.setConfigProperty( BfDependencyCollector.CONFIG_PROP_USE_SKIP, useSkip );
 
-        collector = new DefaultDependencyCollector();
+        collector = new BfDependencyCollector();
         collector.setArtifactDescriptorReader( newReader( "" ) );
         collector.setVersionRangeResolver( new StubVersionRangeResolver() );
         collector.setRemoteRepositoryManager( new StubRemoteRepositoryManager() );
diff --git a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectorUseSkipTest.java b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollectorUseSkipTest.java
similarity index 96%
rename from maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectorUseSkipTest.java
rename to maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollectorUseSkipTest.java
index 716ecdef..5daa678b 100644
--- a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCollectorUseSkipTest.java
+++ b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollectorUseSkipTest.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
@@ -18,6 +18,11 @@ package org.eclipse.aether.internal.impl.collect;
  * under the License.
  */
 
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
 import org.eclipse.aether.artifact.DefaultArtifact;
 import org.eclipse.aether.collection.CollectRequest;
 import org.eclipse.aether.collection.CollectResult;
@@ -29,14 +34,9 @@ import org.eclipse.aether.util.graph.manager.TransitiveDependencyManager;
 import org.eclipse.aether.util.graph.selector.ExclusionDependencySelector;
 import org.junit.Test;
 
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.List;
-
 import static org.junit.Assert.assertEquals;
 
-public class DefaultDependencyCollectorUseSkipTest extends DefaultDependencyCollectorTest
+public class BfDependencyCollectorUseSkipTest extends BfDependencyCollectorTest
 {
 
     private Dependency newDep( String coords, String scope, Collection<Exclusion> exclusions )
diff --git a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCycleTest.java b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCycleTest.java
similarity index 90%
rename from maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCycleTest.java
rename to maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCycleTest.java
index 0a382f8c..a1be7c92 100644
--- a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DefaultDependencyCycleTest.java
+++ b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCycleTest.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -19,6 +19,9 @@ package org.eclipse.aether.internal.impl.collect;
  * under the License.
  */
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.eclipse.aether.artifact.DefaultArtifact;
 import org.eclipse.aether.graph.DefaultDependencyNode;
 import org.eclipse.aether.graph.Dependency;
@@ -26,12 +29,9 @@ import org.eclipse.aether.graph.DependencyCycle;
 import org.eclipse.aether.graph.DependencyNode;
 import org.junit.Test;
 
-import java.util.ArrayList;
-import java.util.List;
-
 import static org.junit.Assert.assertEquals;
 
-public class DefaultDependencyCycleTest
+public class BfDependencyCycleTest
 {
     private static final Dependency FOO_DEPENDENCY = new Dependency( new DefaultArtifact( "group-id:foo:1.0" ), "test" );
     private static final Dependency BAR_DEPENDENCY = new Dependency( new DefaultArtifact( "group-id:bar:1.0" ), "test" );
@@ -41,7 +41,7 @@ public class DefaultDependencyCycleTest
     {
         List<DependencyNode> nodes = new ArrayList<>();
         nodes.add( new DefaultDependencyNode( FOO_DEPENDENCY ) );
-        DependencyCycle cycle = new DefaultDependencyCycle( nodes, 1, BAR_DEPENDENCY );
+        DependencyCycle cycle = new BfDependencyCycle( nodes, 1, BAR_DEPENDENCY );
 
         assertEquals( "group-id:foo:jar -> group-id:bar:jar", cycle.toString() );
     }
diff --git a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DependencyResolutionSkipperTest.java b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/DependencyResolutionSkipperTest.java
similarity index 99%
rename from maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DependencyResolutionSkipperTest.java
rename to maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/DependencyResolutionSkipperTest.java
index 1d92acc0..678b9e76 100644
--- a/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/DependencyResolutionSkipperTest.java
+++ b/maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/collect/bf/DependencyResolutionSkipperTest.java
@@ -1,4 +1,4 @@
-package org.eclipse.aether.internal.impl.collect;
+package org.eclipse.aether.internal.impl.collect.bf;
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
@@ -18,6 +18,12 @@ package org.eclipse.aether.internal.impl.collect;
  * under the License.
  */
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
 import org.eclipse.aether.RepositoryException;
 import org.eclipse.aether.artifact.DefaultArtifact;
 import org.eclipse.aether.graph.DefaultDependencyNode;
@@ -27,12 +33,6 @@ import org.eclipse.aether.internal.test.util.TestVersion;
 import org.eclipse.aether.internal.test.util.TestVersionConstraint;
 import org.junit.Test;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Map;
-import java.util.stream.Collectors;
-
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;