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
* <code>Translation</code> represents a translated message for a specific
	 * locale.
	 * <p>
	 * 
	 * @param translation
	 *            new entry of <code>Translation</code> that are to be added
	 *            to the module.
	 */
	public void addTranslation( Translation translation )
	{
		translations.add( translation );
	}
	/**
	 * Drops a Translation from the module.
	 * <p>
	 * 
	 * @param translation
	 *            the translation to be dropped from the module.
	 * 
	 * @return <code>true</code> if the report module contains the given
	 *         translation.
	 */
	public boolean dropTranslation( Translation translation )
	{
		return translations.remove( translation );
	}
	/**
	 * Finds a <code>Translation</code> by the message resource key and the
	 * locale.
	 * <p>