Bug 182895 Support sort on Level attribute.
Currently in OLAP engine we only support sort on level key value. We should go ahead to support sort on level attribute value.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/olap/query/view/QueryExecutor.java
for ( int k = 0; k < measureAggrOns.size( ); k++ )
				{
					aggrOnLevels[k] = (DimLevel) measureAggrOns.get( k );
				}
			}
			else
			{
				aggrOnLevels = new DimLevel[aggrOns.size( )];
				for ( int j = 0; j < aggrOnLevels.length; j++ )
				{
					aggrOnLevels[j] = OlapExpressionUtil.getTargetDimLevel( aggrOns.get( j )
							.toString( ) );
				}
			}
			DimLevel[] axisLevels = new DimLevel[cubeSort.getAxisQualifierLevels( ).length];
			for ( int k = 0; k < axisLevels.length; k++ )
			{
				axisLevels[k] = new DimLevel( cubeSort.getAxisQualifierLevels( )[k] );
			}
			AggrSortDefinition sort = new AggrSortDefinition( aggrOnLevels,
					bindingName,
					axisLevels,
					cubeSort.getAxisQualifierValues( ),
					new DimLevel( cubeSort.getTargetLevel( ) ),
					cubeSort.getSortDirection( ) == 1 ? false : true );
			if ( isRow )
				cubeQueryExcutorHelper.addRowSort( sort );
			else
				cubeQueryExcutorHelper.addColumnSort( sort );
		}