Bug 161222 Decoration label should be optional in Gantt Chart
It should not be mandatory to specify a decoration label for Gantt Charts, this can be left blank. Currently the UI and Engine enforce a data definition to be specified for it.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/internal/datafeed/ResultSetWrapper.java
{
		private int iSortIndex;
		private boolean ascending;
		private Collator collator;
		void sort( List resultSet, int iSortIndex, SortOption so,
				int[] groupBreaks )
		{
			if ( so == null )
			{
				return;
			}
			this.iSortIndex = iSortIndex;
			this.ascending = so == SortOption.ASCENDING_LITERAL;
			this.collator = Collator.getInstance( );
			if ( groupBreaks == null || groupBreaks.length == 0 )
			{
				Collections.sort( resultSet, this );
			}
			else
			{
				int totalCount = resultSet.size( );
				int startGroupIndex = 0;
				int endGroupIndex;
				List tmpList = new ArrayList( );
				
				for ( int i = 0; i <= groupBreaks.length; i++ )
				{