### Question:
NodeDefinitionHelper { public static String getDiagramId(final Node node) { if (node.getContent() instanceof Definition) { final Object definition = ((Definition) node.getContent()).getDefinition(); if (definition instanceof HasContentDefinitionId) { return ((HasContentDefinitionId) definition).getDiagramId(); } } return null; }  static String getDiagramId(final Node node); static String getContentDefinitionId(final Node node);  }### Answer:
@Test public void testGetDiagram() { final String diagramId = "diagramId"; final Node node = createNode("id", diagramId); final String actual = getDiagramId(node); assertEquals(diagramId, actual); }