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
lhmRenderers,
				rtc,
				oComputations );
		if ( sh != null )
		{
			sh.setGeneratedChartState( gcs );
			ScriptHandler.callFunction( sh,
					ScriptHandler.FINISH_GENERATION,
					gcs );
			ScriptHandler.callFunction( sh,
					ScriptHandler.AFTER_GENERATION,
					gcs,
					rtc.getScriptContext( ) );
		}
		return gcs;
	}
	/**
	 * Performs a minimal rebuild of the chart if non-sizing attributes are
	 * altered or the dataset for any series has changed. However, if sizing
	 * attribute changes occur that affects the relative position of the various
	 * chart subcomponents, a re-build is required.
	 * 
	 * @param gcs
	 *            A previously built chart encapsulated in a transient
	 *            structure.
	 * 
	 * @throws ChartException
	 */
	public final void refresh( GeneratedChartState gcs ) throws ChartException
	{