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
* 
	 * @return the list of exception
	 */
	public List getAllExceptions( )
	{
		return allExceptions;
	}
	/**
	 * Returns the validation executor.
	 * 
	 * @return the validation executor
	 */
	public ValidationExecutor getValidationExecutor( )
	{
		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 );
	}
	/**