### Question:
CaseManagementCommandUtil { @SuppressWarnings("unchecked") public static Node<Definition<CaseManagementDiagram>, ?> getFirstDiagramNode(final Graph<?, Node> graph) { return GraphUtils.getFirstNode(graph, CaseManagementDiagram.class); }  @SuppressWarnings("unchecked") static Node<Definition<CaseManagementDiagram>, ?> getFirstDiagramNode(final Graph<?, Node> graph); @SuppressWarnings("unchecked") static int getChildGraphIndex(final Node parent,
                                         final Node child); @SuppressWarnings("unchecked") static int getChildCanvasIndex(final Node<View<?>, Edge> parent,
                                          final Node<View<?>, Edge> child); static boolean isStage(final Node<View<?>, Edge> parent, final Node<View<?>, Edge> child); static boolean isStageNode(final Node<View<?>, Edge> node); static boolean isSubStageNode(final Node<View<?>, Edge> node); static Predicate<Edge> childPredicate(); static Predicate<Edge> sequencePredicate(); @SuppressWarnings("unchecked") static int getNewChildCanvasIndex(final Node<View<?>, Edge> parent); @SuppressWarnings("unchecked") static int getNewChildGraphIndex(final Node<View<?>, Edge> parent);  }### Answer:
@Test public void checkGetFirstDiagramNodeWithEmptyGraph() { final Graph graph = new GraphImpl<>("uuid", new GraphNodeStoreImpl()); final Node<Definition<CaseManagementDiagram>, ?> fNode = CaseManagementCommandUtil.getFirstDiagramNode(graph); assertNull(fNode); }
@Test @SuppressWarnings("unchecked") public void checkGetFirstDiagramNodeWithNonEmptyGraph() { final Graph graph = new GraphImpl<>("uuid", new GraphNodeStoreImpl()); final Node node = new NodeImpl<Definition>("node-uuid"); final CaseManagementDiagram content = new CaseManagementDiagram(); node.setContent(new DefinitionImpl<>(content)); graph.addNode(node); final Node<Definition<CaseManagementDiagram>, ?> fNode = CaseManagementCommandUtil.getFirstDiagramNode(graph); assertNotNull(fNode); assertEquals("node-uuid", fNode.getUUID()); assertEquals(content, fNode.getContent().getDefinition()); }