Bug 192083 [regression]DataException when preview attached xtab report.[1102]
data/org.eclipse.birt.report.data.adapter/src/org/eclipse/birt/report/data/adapter/impl/DataRequestSessionImpl.java
leafLevelKeyColumn[k] = level.getName( );
				
				levelInHier[k] = CubeElementFactory.createLevelDefinition( level.getName( ),
						new String[]{
							level.getName( )
						},
						this.toStringArray( levelKeys ) );
			}
			
			createLeafLevel( levels, levelInHier, leafLevelKeyColumn );
		
			iHiers.add( cubeMaterializer.createHierarchy( dim.getName( ), hierhandle.getName( ),
					new DataSetIterator( this, hierhandle ),
					levelInHier ) );
		}
		return cubeMaterializer.createDimension( dim.getName( ),
				(IHierarchy) iHiers.get( 0 ) ) ;
	}
	/**
	 * 
	 * @param levels
	 * @param levelInHier
	 * @param leafLevelKeyColumn
	 */
	private void createLeafLevel( List levels, ILevelDefn[] levelInHier,
			String[] leafLevelKeyColumn )
	{
		if( levelInHier.length > levels.size() )
		{
			levelInHier[levelInHier.length-1] = CubeElementFactory.createLevelDefinition( "_${INTERNAL_INDEX}$_",