backbone should be done

src/graph/Edge.java

@@ -1,6 +0,0 @@
-package graph;
-
-public class Edge<T> {
-    Node<T> node1;
-    Node<T> node2;
-}

src/graph/Graph.java

@@ -1,4 +1,11 @@
 package graph;
 
-public class Graph {
+import java.util.List;
+
+public abstract class Graph {
+    protected List<Node> nodes;
+
+    public List<Node> getAllNodes() {
+        return nodes;
+    }
 }

src/graph/Node.java

@@ -1,5 +1,20 @@
 package graph;
 
-public class Node<T> {
-    T item;
+import java.util.List;
+
+public abstract class Node {
+    private final String item;
+    private List<Node> children;
+
+    public Node(String item) {
+        this.item = item;
+    }
+
+    public String getItem() {
+        return item;
+    }
+
+    public List<Node> getChildren() {
+        return children;
+    }
 }