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/Module.java
*            be used instead.
	 * @return the corresponding locale-dependent messages. Return
	 *         <code>""</code> if translation can not be found, or
	 *         <code>resourceKey</code> is blank or <code>null</code>.
	 */
	public String getMessage( String resourceKey, ULocale locale )
	{
		if ( StringUtil.isBlank( resourceKey ) )
			return ""; 
		if ( locale == null )
			locale = ThreadResources.getLocale( );
		
		String msg = translations.getMessage( resourceKey, locale );
		if ( msg != null )
			return msg;
		
		String baseName = getStringProperty( this, INCLUDE_RESOURCE_PROP );
		if ( baseName == null )
			return ""; 
		
		msg = BundleHelper.getHelper( this, baseName ).getMessage( resourceKey,
				locale );
		return msg;
	}
	/**
	 * Return the folder in which the design file is located. The search depend
	 * on the {@link #getFileName()}.
	 * 
	 * @return the folder in which the design file is located. Return
	 *         <code>null</code> if the folder can not be found.