Bug 179743 Parameter Validate Event is not Called
I have tested the validate event on parameters and it never appears to get called.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
* <li> engine level format options</li>
	 * <li> engine level emitter options</li>
	 * <li> task level options </li>
	 * 
	 */
	protected void setupRenderOption( )
	{
		String format = RenderOption.OUTPUT_FORMAT_HTML;;
		if ( renderOptions != null )
		{
			format = renderOptions.getOutputFormat( );
			if ( format == null || format.length( ) == 0 )
			{
				format = RenderOption.OUTPUT_FORMAT_HTML;
				renderOptions.setOutputFormat( format );
			}
		}
		
		Map appContext = executionContext.getAppContext( );
		if ( IRenderOption.OUTPUT_FORMAT_PDF.equals( format ) )
		{
			Object renderContext = appContext
					.get( EngineConstants.APPCONTEXT_PDF_RENDER_CONTEXT );
			if ( renderContext instanceof PDFRenderContext )
			{
				PDFRenderContext pdfContext = (PDFRenderContext) renderContext;
				mergeOption( renderOptions, PDFRenderOption.BASE_URL,
						pdfContext.getBaseURL( ) );
				mergeOption( renderOptions, PDFRenderOption.FONT_DIRECTORY,
						pdfContext.getFontDirectory( ) );