Graph graph = new Graph();
        graph.addVertex("a");
        assertEquals(1, graph.getVertices().size());
        assertEquals("a", graph.getVertex("a").getLabel());
        graph.addVertex("a");
        assertEquals(1, graph.getVertices().size());
        assertEquals("a", graph.getVertex("a").getLabel());

        graph.addVertex("b");
        assertEquals(2, graph.getVertices().size());
        assertFalse(hasEdge(graph, "a", "b"));

        return sortedProjects.size() > 1;
    }

    public List<String> getDependents(String id) {
        return graph.getVertex(id).getParents().stream().map(Vertex::getLabel).collect(Collectors.toList());
    }

    public List<String> getDependencies(String id) {
        return graph.getVertex(id).getChildren().stream().map(Vertex::getLabel).collect(Collectors.toList());
    }

import java.util.Map;

class Graph {
    private enum DfsState {
        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);
    }

    public Collection<Vertex> getVertices() {
        return vertices.values();
    }

    Vertex addVertex(String label) {

import java.util.Map;

class Graph {
    private enum DfsState {
        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);
    }

    public Collection<Vertex> getVertices() {
        return vertices.values();
    }

    Vertex addVertex(String label) {

Vertex addVertex(String); public void addEdge(String, String) throws CycleDetectedExcepti; public void addEdge(Vertex, Vertex) throws CycleDetectedExcepti; public void removeEdge(String, String); public void removeEdge(Vertex, Vertex); public Vertex getVertex(String); public boolean hasEdge(String, String); public java.util.List getChildLabels(String); public java.util.List getParentLabels(String); public Object clone() throws CloneNotSupportedExc; public boolean isConnected(String); public java.util.List...