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
final Iterator it = resultSet.iterator( );
		final ArrayList al = new ArrayList( 8 );
		boolean bFirst = true;
		Object oValue, oPreviousValue = null;
		int iRowIndex = 0;
		while ( it.hasNext( ) )
		{
			oValue = ( (Object[]) it.next( ) )[iColumnIndex];
			iRowIndex++;
			if ( bFirst )
			{
				bFirst = false;
				oPreviousValue = oValue;
				continue;
			}
			if ( compareObjects( oPreviousValue, oValue ) != 0 )
			{
				al.add( new Integer( iRowIndex - 1 ) );
			}
			oPreviousValue = oValue;
		}
		final int[] ia = new int[al.size( )];
		for ( int i = 0; i < al.size( ); i++ )
		{
			ia[i] = ( (Integer) al.get( i ) ).intValue( );
		}
		return ia;
	}
	/**
	 * Compares two objects of the same data type