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
int maxLen = baseValue.size( );
		for ( Iterator itr = idxList.iterator( ); itr.hasNext( ); )
		{
			List lst = (List) itr.next( );
			if ( lst.size( ) < maxLen )
			{
				int inc = maxLen - lst.size( );
				for ( int i = 0; i < inc; i++ )
				{
					lst.add( new Integer( -1 ) );
				}
			}
		}
		return new Object[]{
				baseValue, idxList
		};
	}
	/**
	 * Returns the data type of specified column.
	 * 
	 * @param iColumnIndex
	 * @return
	 */
	public int getColumnDataType( int iColumnIndex )
	{
		return iaDataTypes[iColumnIndex];
	}
	/**
	 * Returns the iterator of associated resultset.
	 *