{

    private static Log log;

    private static I18N i18n;

    private boolean uniqueVersions;

    public void setUniqueVersions( boolean uniqueVersions )
    {
        this.uniqueVersions = uniqueVersions;
    }

    // CHECKSTYLE_OFF: LineLength
    /**
     * Uses the {@link EnforcerRuleHelper} to populate the values of the
     * {@link DependencyTreeBuilder#buildDependencyTree(MavenProject, ArtifactRepository, ArtifactFactory, ArtifactMetadataSource, ArtifactFilter, ArtifactCollector)}
     * factory method. <br/>
     * This method simply exists to hide all the ugly lookup that the {@link EnforcerRuleHelper} has to do.
     * 
     * @param helper
     * @return a Dependency Node which is the root of the project's dependency tree
     * @throws EnforcerRuleException
     */
    // CHECKSTYLE_ON: LineLength
    private DependencyNode getNode( EnforcerRuleHelper helper )
        throws EnforcerRuleException
    {
        try
        {
            MavenProject project = (MavenProject) helper.evaluate( "${project}" );
            DependencyTreeBuilder dependencyTreeBuilder =
                (DependencyTreeBuilder) helper.getComponent( DependencyTreeBuilder.class );
            ArtifactRepository repository = (ArtifactRepository) helper.evaluate( "${localRepository}" );
            ArtifactFactory factory = (ArtifactFactory) helper.getComponent( ArtifactFactory.class );
            ArtifactMetadataSource metadataSource =
                (ArtifactMetadataSource) helper.getComponent( ArtifactMetadataSource.class );
            ArtifactCollector collector = (ArtifactCollector) helper.getComponent( ArtifactCollector.class );
            ArtifactFilter filter = null; // we need to evaluate all scopes
            DependencyNode node =
                dependencyTreeBuilder.buildDependencyTree( project, repository, factory, metadataSource, filter,
                                                           collector );
            return node;
        }
        catch ( ExpressionEvaluationException e )
        {
            throw new EnforcerRuleException( "Unable to lookup an expression " + e.getLocalizedMessage(), e );
        }
        catch ( ComponentLookupException e )
        {
            throw new EnforcerRuleException( "Unable to lookup a component " + e.getLocalizedMessage(), e );
        }
        catch ( DependencyTreeBuilderException e )
        {
            throw new EnforcerRuleException( "Could not build dependency tree " + e.getLocalizedMessage(), e );
        }
    }

    public void execute( EnforcerRuleHelper helper )
        throws EnforcerRuleException
    {
        if ( log == null )
        {
            log = helper.getLog();
        }
        try
        {
            if ( i18n == null )
            {
                i18n = (I18N) helper.getComponent( I18N.class );
            }
            DependencyNode node = getNode( helper );