<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
   "-//Hibernate/Hibernate Mapping DTD//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

<hibernate-mapping>
   <class name="Category" table="category">
      <meta attribute="sync-DAO">true</meta>
      <id name="id" type="integer" column="categoryID">
         <generator class="sequence" />
      </id>

      <property name="name" column="name" type="string"
         not-null="true" length="200" />
      <many-to-one name="parentID" column="parentID" class="Category"
         not-null="false">
      </many-to-one>

      <set name="categories" inverse="true" lazy="true">
         <key column="categoryID" />
         <one-to-many class="Category" />
      </set>

   </class>
</hibernate-mapping>

public class CategoryBLL {

   /**
    * Creates a new category with the given name and no parent;
    * @param name The name of the category to create.
    * @return The newly created category.
    */
   public static Category create(String name) {      
      return create(name, null);
   }
   
   /**
    * Creates a new category with the given name and parent.
    * @param name The name of the new category.
    * @param parent The parent of the new category.
    * @return The newly created category
    */
   public static Category create(String name, Category parent) {
      if (null == name || name.equals("")) {
         throw new IllegalArgumentException("name cannot be null or empty");
      }
      
      HibernateUtil.init();
      
      CategoryDAO dao = (CategoryDAO) CategoryDAO.getInstance();
      
      Transaction tx = dao.getSessionFactory().openSession().beginTransaction();
      
      Category c = new Category();
      c.setName(name);
      c.setParentID(parent);
      
      dao.save(c);
      
      if (null != parent) {
         addChild(parent, c);
      }
      
      tx.commit();
      
      return c;
   }
   
   /**
    * Adds a child to a parent category.
    * @param parent The parent category.
    * @param child The child category to add.
    */
   public static void addChild(Category parent, Category child) {
      if (null == parent) {
         throw new IllegalArgumentException("parent cannot be null");
      }
      
      if (null == child) {
         throw new IllegalArgumentException("child cannot be null");
      }
      
      if (null == parent.getCategories()) {
         parent.setCategories(new HashSet<Category>());
      }
      
      parent.getCategories().add(child);
      
      update(parent);
   }
   
   /**
    * Updates a modified category.
    * @param category The category to update.
    */
   public static void update(Category category) {
      HibernateUtil.init();
      
      CategoryDAO dao = (CategoryDAO) CategoryDAO.getInstance();
      
      dao.update(category);
   }
   
   /**
    * Gets a category by its name.
    * @param id The name of the category to get.
    * @return The category with given name.
    */
   public static Category getByName(String name) {
      HibernateUtil.init();
      
      CategoryDAO dao = (CategoryDAO) CategoryDAO.getInstance();

      Query q = dao.getSession().createQuery("from Category where name = :name");
      q.setParameter("name", name);
      
      return (Category) q.uniqueResult();
   }
}

public class CategoryBLLTest {
   @Before
   public void initDB() {
      _RootDAO.initialize();
   }
   
   @After
   public void closeSession() {
      _RootDAO.closeCurrentSession();
   }

   @Test
   public void testBugGetCategories() {
      String name = "Watches";
      
      CategoryBLL.create(name);
      
      Category c1 = CategoryBLL.getByName(name);
      
      Set<Category> children = c1.getCategories();
      
      Assert.assertEquals(0, children.size());
   }
}

Hibernate: select next value for hibernate_sequence from dual_hibernate_sequence
Hibernate: insert into category (name, parentID, categoryID) values (?, ?, ?)
Hibernate: select category0_.categoryID as categoryID37_, category0_.name as name37_, category0_.parentID as parentID37_ from category category0_ where category0_.name=?
Hibernate: select categories0_.categoryID as categoryID1_, categories0_.categoryID as categoryID37_0_, categories0_.name as name37_0_, categories0_.parentID as parentID37_0_ from category categories0_ where categories0_.categoryID=?