}

    @Override
    public List<ArtifactVersion> retrieveAvailableVersions(MetadataResolutionRequest request)
            throws ArtifactMetadataRetrievalException {
        return retrieveAvailableVersions(
                request.getArtifact(), request.getLocalRepository(), request.getRemoteRepositories());
    }

    /**
     * Retrieves a list of remote repositories associated with this session.
     *
     * @return a list of remote repositories
     */
    @Nonnull
    List<RemoteRepository> getRemoteRepositories();

    /**
     * Retrieves the session data associated with this session.
     *
     * @return the session data, never {@code null}
     */
    @Nonnull
    SessionData getData();

    /**

        }

        ResolutionGroup cached = cache.get(
                artifact,
                request.isResolveManagedVersions(),
                request.getLocalRepository(),
                request.getRemoteRepositories());

        if (cached != null
                // if the POM has no file, we cached a missing artifact, only return the cached data if no update forced

            }

            @Override
            public List<ArtifactVersion> retrieveAvailableVersions(MetadataResolutionRequest request) {
                return retrieveAvailableVersions(
                        request.getArtifact(), request.getLocalRepository(), request.getRemoteRepositories());
            }
        };

        ResolutionNode root = new ResolutionNode(originatingArtifact, repositoryRequest.getRemoteRepositories());

        try {
            root.addDependencies(artifacts, repositoryRequest.getRemoteRepositories(), filter);
        } catch (CyclicDependencyException e) {
            result.addCircularDependencyException(e);

            return result;

        artifact.setFile(localFile);

        if (!localFile.exists()) {
            if (request.getRemoteRepositories().isEmpty()) {
                throw new IOException(localFile + " does not exist and no remote repositories are configured");
            }

            ArtifactRepository remoteRepo = request.getRemoteRepositories().get(0);

            File remoteFile = new File(remoteRepo.getBasedir(), remoteRepo.pathOf(artifact));

    }

    @Override
    public ResolutionGroup retrieve(MetadataResolutionRequest request) throws ArtifactMetadataRetrievalException {
        return retrieve(request.getArtifact(), request.getLocalRepository(), request.getRemoteRepositories());
    }

    }

    @Override
    public ResolutionGroup retrieve(MetadataResolutionRequest request) {
        return retrieve(request.getArtifact(), request.getLocalRepository(), request.getRemoteRepositories());
    }

        // as well as its dependencies.

        if (request.isResolveRoot() /* && rootArtifact.getFile() == null */) {
            try {
                resolve(rootArtifact, request.getRemoteRepositories(), session);
            } catch (ArtifactResolutionException e) {
                result.addErrorArtifactException(e);
                return result;
            } catch (ArtifactNotFoundException e) {

        try {
            List<ArtifactRepository> repositories = session.toArtifactRepositories(
                    request.getRepositories() != null ? request.getRepositories() : session.getRemoteRepositories());
            ProjectBuildingRequest req = new DefaultProjectBuildingRequest()
                    .setRepositorySession(session.getSession())
                    .setRemoteRepositories(repositories)