Bug 193467 URL hyperlink can't work in chart viewer
chart/org.eclipse.birt.chart.viewer/src/org/eclipse/birt/chart/viewer/sample/SampleHelper.java
{
			column = (Object[]) map.get( expression );
			return column[k];
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.birt.chart.factory.IDataRowExpressionEvaluator#first()
		 */
		public boolean first( )
		{
			k = 0;
			if ( map.size( ) > 0 )
			{
				column = (Object[]) map.values( ).iterator( ).next( );
				if ( column != null && k < column.length )
				{
					return true;
				}
			}
			return false;
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.birt.chart.factory.IDataRowExpressionEvaluator#next()
		 */
		public boolean next( )
		{
			if ( column != null && k < ( column.length - 1 ) )