Bug 140542 label can't be displayed without resource file or unmatched key
Steps to reproduce: 1.New a report, add a lable with text "aaa" 2.Add a resource file for the report, set key to "key1", value to "actuate", apply the value to the label 3.Clear the resource file in Property Editor->General->Resource File (or change the key to "abc") 4.Preview the report Expected result: 1.Display label text "aaa" on preview or 2.Give a warning message to say resource file is not found or unmatched key Actual result: Nothing displays on preview
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/BundleHelper.java
* 
	 * @param module
	 *            the module
	 * @param baseName
	 *            base name of the resource bundle. The name is a common base
	 *            name
	 * @return a correspondent helper instance. Return <code>null</code> if
	 *         the <code>msgFolder</code> is null or not a directory.
	 * 
	 */
	public static BundleHelper getHelper( Module module, String baseName )
	{
		assert module != null;
		return new BundleHelper( module, baseName );
	}
	/**
	 * Return a collection of user-defined message keys in the referenced
	 * message files for the given locale. If the input <code>locale</code> is
	 * <code>null</code>, the locale for the current thread will be used
	 * instead.
	 * 
	 * @param locale
	 *            locale to use when finding the bundles.
	 * @return a list of user-defined message keys in the referenced message
	 *         files.
	 */
	public Collection getMessageKeys( ULocale locale )
	{
		Set keys = new LinkedHashSet( );
		Iterator bundleIter = gatherMessageBundles( locale ).iterator( );