Bug 145520 Group name will not show up in group list if the group use default name and key expression has no value
Description: Group name will not show up in group list if key expression has no value. Steps to reproduce: 1. Insert a table into report, bind it to a data set 2. Switch to property editor -> groups 3. Click on add button to open new group dialog, then press ok button Expected result: A new group with default name will be added to group list Actual result: A new group is added to group list, but without group name. But when let group tab lost focus and get focus again, you can see the group name.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
* The validation executor. It performs the semantic validation and sends
	 * validation event to listeners.
	 */
	protected ValidationExecutor validationExecutor = new ValidationExecutor(
			this );
	/**
	 * The listener list for validation event.
	 */
	private List validationListeners = null;
	/**
	 * The file name. Null means that the module has not yet been saved to a
	 * file.
	 */
	protected String fileName = null;
	/**
	 * The system id which is needed for resolving relative URIs. It can be a
	 * relative/absolute file directory or a network path such as HTTP, FTP,
	 * etc.
	 */
	protected URL systemId = null;
	/**
	 * The UTF signature.
	 */
	protected String signature = null;
	/**
	 * The default units for the design.
	 */
	protected String units = null;
	/**
	 * All libraries which are included in this module.