Bug 167511 [Block]NPE when using customized IStyleProcessor with Chart Generator and no Chart will be rendered
Use a customized IStyleProcessor with Generator.build() and the chart will not be rendered in UI.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/factory/Generator.java
*            An IActionEvaluator instance
	 * @return All row expressions in a list of String instances.
	 * @throws ChartException
	 * 
	 * @since 2.0
	 */
	public List getRowExpressions( Chart cm, IActionEvaluator iae )
			throws ChartException
	{
		if ( cm instanceof ChartWithAxes )
		{
			return getRowExpressions( (ChartWithAxes) cm, iae );
		}
		else if ( cm instanceof ChartWithoutAxes )
		{
			return getRowExpressions( (ChartWithoutAxes) cm, iae );
		}
		return null;
	}
	/**
	 * Binds a sql Resuset to a chart model. This is based on the assumption the
	 * column names of the resultset match exactly the data query definitions
	 * and other expressions set inside the chart model.
	 * 
	 * @param resultSet
	 *            A sql resultset that contains the data. The following methods
	 *            of the interface need to be implemented: first(), next(),
	 *            getObject(String), close()
	 * @param chart
	 *            The chart model to bind the data to