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
/**
	 * logger used to output the message
	 */
	protected Logger log;
	/**
	 * Comment for <code>locale</code>
	 */
	protected Locale locale = Locale.getDefault( );
	/**
	 * the execution context
	 */
	protected ExecutionContext executionContext;
	/**
	 * task identifier. Could be used for logging
	 */
	protected int taskID;
	protected IReportRunnable runnable;
	/**
	 * options used to render the report design.
	 */
	protected IRenderOption renderOptions;
	/**
	 * emitter id
	 */
	protected String emitterID;
	/**
	 * does the parameter has been changed by the user.
	 */
	protected boolean parameterChanged = true;
	/**