### Question:
EmptyConstructor implements EmptyTreeConstructor<E, MutableSettableStructuredNode<E>, LinkedTree<E>> { @Override public LinkedTree<E> build() { return new LinkedTree<>(null); }  @Override LinkedTree<E> build(); @Override Class<? extends Tree> forClass();  }### Answer:
@Test public void build() { final EmptyConstructor<String> constructor = new EmptyConstructor<>(); final LinkedTree<String> tree = constructor.build(); assertTrue(tree.isEmpty()); }