### Question:
Node extends GraphObject { public long getId() { return id; } Node();  Node(long id); long getId(); void setId(long id); void addComponent(NodeComponent component); void addComponent(Class<? extends NodeComponent> key, NodeComponent component); C getComponent(Class<C> componentClass); boolean hasComponent(Class<? extends NodeComponent> key); Set<Class<? extends NodeComponent>> getAllComponentClasses(); @Override boolean equals(Object obj); @Override int hashCode();  }### Answer:
@Test public void testGetId() { assertEquals(0l, n.getId()); }