### Question:
DefaultTreeWalker implements TreeWalker<E> { @Override public void onStarted() { }  @Override void onStarted(); @Override void onNode(E node); @Override void onNodeChildrenStarted(E node); @Override void onNodeChildrenRemaining(E node); @Override void onNodeChildrenCompleted(E node); @Override void onNodeNoChildren(E node); @Override void onCompleted();  }### Answer:
@Test public void testOnStarted() throws Exception { WALKER.onStarted(); }