<class name="jobprep.domain.Question" table="question">
        <id name="id" column="question_id" type="long">
            <generator class="sequence">
                <param name="sequence">question_id_sequence</param>
            </generator>
        </id>
        <property name="text" column="text"/>
       <bag name="answers" inverse="true" cascade="all-delete-orphan">
           <key column="answer_id" not-null="true"/>
           <one-to-many class="jobprep.domain.Answer" />
       </bag>
        <bag name="hints" inverse="true" cascade="all-delete-orphan">
            <key column="hint_id" not-null="true"/>
            <one-to-many class="jobprep.domain.Hint"/>
        </bag>
        <property name="points" column="points"/>
    </class>

public class Question extends DomainObject {

   /* Members */
   private String text;
   List<Answer> answers = new ArrayList<Answer>();
   List<Hint> hints = new ArrayList<Hint>();
   private int points;

   /* Constructors */
   public Question() {

   }

   public Question( String text, Answer answer, int points ) {
      this.text = text;
      this.addAnswer( answer );
      this.points = points;
   }

   /* Services */
   public void addAnswer( Answer answer ) {
      Util.checkNullArgument( answer, "answer" );

      answers.add( answer );
   }

   public void removeAnswer( Answer answer ) {
      answers.remove( answer );
   }

   public boolean supplyAnswer( String answerText ) {
      for( Answer answer : answers ) {
         if( answer.matches( answerText ) ) {
            return true;
         }
      }

      return false;
   }

   public void addHint( Hint hint ) {
      Util.checkNullArgument( hint, "hint" );

      hints.add( hint );
   }

   public void removeHint( Hint hint ) {
      hints.remove( hint );
   }

   public Hint findHintByAttemptsNeeded( int attempts ) {
      sortHints();

      for( Hint hint : hints ) {
         if( attempts >= hint.getAttemptsNeeded() ) {
            return hint;
         }
      }

      return null;
   }

   void sortHints() {
      sort( hints, new Comparator<Hint>() {
         public int compare( Hint hint1, Hint hint2 ) {
            return hint2.getAttemptsNeeded() - hint1.getAttemptsNeeded();
         }

      } );
   }

   public int getHintThreshold() {
      int hintThreshold = Integer.MAX_VALUE;

      for( Hint hint : hints ) {
         if( hint.getAttemptsNeeded() < hintThreshold ) {
            hintThreshold = hint.getAttemptsNeeded();
         }
      }

      return hintThreshold;
   }

   /* Properties */
   public String getText() {
      return text;
   }

   public void setText( String text ) {
      this.text = text;
   }

   public List<Answer> getAnswers() {
      return answers;
   }

   public void setAnswers( List<Answer> answers ) {
      this.answers = answers;
   }

   public List<Hint> getHints() {
      return hints;
   }

   public void setHints( List<Hint> hints ) {
      this.hints = hints;
   }

   public int getPoints() {
      return points;
   }

   public void setPoints( int points ) {
      this.points = points;
   }

}

public class DomainObject implements Serializable {

   /* Members */
   private long id;

   /* Constructors */

   /* Services */

   @Override
   public boolean equals( Object o ) {
      if( this == o ) return true;
      if( !( o instanceof DomainObject ) ) return false;

      DomainObject that = ( DomainObject ) o;

      if( id != that.id ) return false;

      return true;
   }

   @Override
   public int hashCode() {
      return ( int ) ( id ^ ( id >>> 32 ) );
   }

   /* Properties */
   public long getId() {
      return id;
   }

   public void setId( long id ) {
      this.id = id;
   }
}

   public Question find( long id ) {
      Question question = ( Question ) sessionFactory.getCurrentSession().createQuery(
          "from Question question where question.id = :id" )
         .setParameter( "id", id )
         .uniqueResult();

      if( question != null ) {
         Hibernate.initialize( question.getHints() );
         Hibernate.initialize( question.getAnswers() );
      }

      return question;
   }