public CriteriaJoinWalker(OuterJoinLoadable persister,
    CriteriaQueryTranslator translator,
    SessionFactoryImplementor factory,
    CriteriaImpl criteria,
    String rootEntityName,
    Map enabledFilters) 
{
		this(persister, translator, factory, criteria, rootEntityName, enabledFilters, null);
}

 public CriteriaJoinWalker(OuterJoinLoadable persister,
    CriteriaQueryTranslator translator,
    SessionFactoryImplementor factory,
    CriteriaImpl criteria,
    String rootEntityName,
    Map enabledFilters,
    String alias) 
{
		super(persister, factory, enabledFilters, alias);
		this.translator = translator;
		querySpaces = translator.getQuerySpaces();
		if ( translator.hasProjection() ) {
			resultTypes = translator.getProjectedTypes();
			initProjection( 
					translator.getSelect(), 
					translator.getWhereCondition(), 
					translator.getOrderBy(),
					translator.getGroupBy(),
					LockMode.NONE 
				);
		}
		else {
			resultTypes = new Type[] { TypeFactory.manyToOne( persister.getEntityName() ) };
			initAll( translator.getWhereCondition(), translator.getOrderBy(), LockMode.NONE );
		}
		userAliasList.add( criteria.getAlias() ); //root entity comes *last*
		userAliases = ArrayHelper.toStringArray(userAliasList);
}

 protected String generateRootAlias(String tableName) 
{
		return CriteriaQueryTranslator.ROOT_SQL_ALIAS;
}

 protected String generateTableAlias(int n,
    String path,
    Joinable joinable) 
{
		if ( joinable.consumesEntityAlias() ) {
			final Criteria subcriteria = translator.getCriteria(path);
			String sqlAlias = subcriteria==null ? null : translator.getSQLAlias(subcriteria);
			if (sqlAlias!=null) {
				userAliasList.add( subcriteria.getAlias() ); //alias may be null
				return sqlAlias; //EARLY EXIT
			}
			else {
				userAliasList.add(null);
			}
		}
		return super.generateTableAlias( n + translator.getSQLAliasCount(), path, joinable );
}

 public String getComment() 
{
		return "criteria query";
}

 protected int getJoinType(AssociationType type,
    FetchMode config,
    String path,
    String lhsTable,
    String[] lhsColumns,
    boolean nullable,
    int currentDepth,
    CascadeStyle cascadeStyle) throws MappingException 
{
		if ( translator.isJoin(path) ) {
			return translator.getJoinType( path );
		}
		else {
			if ( translator.hasProjection() ) {
				return -1;
			}
			else {
				FetchMode fetchMode = translator.getRootCriteria()
					.getFetchMode(path);
				if ( isDefaultFetchMode(fetchMode) ) {
					return super.getJoinType(
							type, 
							config, 
							path, 
							lhsTable, 
							lhsColumns, 
							nullable,
							currentDepth, cascadeStyle
						);
				}
				else {
					if ( fetchMode==FetchMode.JOIN ) {
						isDuplicateAssociation(lhsTable, lhsColumns, type); //deliberately ignore return value!
						return getJoinType(nullable, currentDepth);
					}
					else {
						return -1;
					}
				}
			}
		}
}

 public Set getQuerySpaces() 
{
		return querySpaces;
}

 public Type[] getResultTypes() 
{
	   
		return resultTypes;
}

 public String[] getUserAliases() 
{
		return userAliases;
}

 protected String getWhereFragment() throws MappingException 
{
		return super.getWhereFragment() +
			( (Queryable) getPersister() ).filterFragment( getAlias(), getEnabledFilters() );
}

Use the discriminator, to narrow the select to instances of the queried subclass, also applying any filters.