(first..last).each {
            classToproject.put(it, project)
            placeNode(it, CLASSES_ON_LEVEL, classDependencyTrees.computeIfAbsent(project) {[]}, parentToChildClassIds)
        }
        this
    }

    DependencyTree calculateProjectDependencies() {
        (0..classDependencyTrees.size() - 1).each {
            placeNode(it, PROJECTS_ON_LEVEL, projectDependencyTree, parentToChildProjectIds)
        }