Bug 214196 [Automation][Compatibility]Exception occurs when preview a old crosstab with measure sorting
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/DataEngineImpl.java
* @see org.eclipse.birt.data.engine.api.DataEngine#addShutdownListener(org.eclipse.birt.data.engine.api.IShutdownListener)
	 */
	public void addShutdownListener( IShutdownListener listener )
	{
		if ( shutdownListenerList == null )
			shutdownListenerList = new ArrayList( );
		for ( int i = 0; i < shutdownListenerList.size( ); i++ )
		{
			if ( listener == shutdownListenerList.get( i ) )
				return;
		}
		shutdownListenerList.add( listener );
	}
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.birt.data.engine.api.DataEngine#removeListener(org.eclipse.birt.data.engine.api.IShutdownListener)
	 */
	public void removeListener( IShutdownListener listener )
	{
		if ( shutdownListenerList == null )
			return;
		for ( int i = 0; i < shutdownListenerList.size( ); i++ )
		{
			if ( listener == shutdownListenerList.get( i ) )
			{
				shutdownListenerList.remove( i );
				return;
			}
		}
	}