Bug 197228 Need updaet createdBy info when serialize the module
When open module, designer will pass the property map which contains the createdBy info. this info should be retained by moduleHandle and then be updated and written when doing serialization. Note if this info is null, model should not update it during serialization. This could happen for api users or third-party designer. For BIRT designer, it will guarantee this value always not null.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
{
		return validationExecutor;
	}
	/**
	 * Adds one validation listener. The duplicate listener will not be added.
	 * 
	 * @param listener
	 *            the validation listener to add
	 */
	public void addValidationListener( IValidationListener listener )
	{
		if ( validationListeners == null )
			validationListeners = new ArrayList( );
		if ( !validationListeners.contains( listener ) )
			validationListeners.add( listener );
	}
	/**
	 * Removes one validation listener. If the listener not registered, then the
	 * request is silently ignored.
	 * 
	 * @param listener
	 *            the validation listener to remove
	 * @return <code>true</code> if <code>listener</code> is sucessfully
	 *         removed. Otherwise <code>false</code>.
	 * 
	 */
	public boolean removeValidationListener( IValidationListener listener )
	{
		if ( validationListeners == null )
			return false;