### Question:
ParentReferenceFactoryImpl implements ParentReferenceFactory<E, MutableBinaryTreeNode<E>> { @Override public Class<?> forClass() { return MutableBinaryTreeNodeImpl.class; }  @Override ParentReference<MutableBinaryTreeNode<E>> wrap(MutableBinaryTreeNode<E> node); @Override ParentReference<MutableBinaryTreeNode<E>> wrap(Tree<E, MutableBinaryTreeNode<E>> tree); @Override Class<?> forClass();  }### Answer:
@Test public void forClass() { final ParentReferenceFactoryImpl<String> factory = new ParentReferenceFactoryImpl<>(); assertEquals(MutableBinaryTreeNodeImpl.class, factory.forClass()); }