Bug 147687 Assert err happened with design ui
Run BIRT in workbench with argument -ea. Assert err happened when using design ui to open a design file.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dialogs/ExpressionTreeSupport.java
methodList.add( classInfo.getConstructor( ) );
			methodList.addAll( classInfo.getMethods( ) );
			for ( Iterator iterator = methodList.iterator( ); iterator.hasNext( ); )
			{
				IMethodInfo methodInfo = (IMethodInfo) iterator.next( );
				if ( methodInfo == null )
				{
					
					continue;
				}
				Image image = globalImage;
				if ( image == null )
				{
					if ( methodInfo.isStatic( ) )
					{
						image = IMAGE_STATIC_METHOD;
					}
					else
					{
						image = IMAGE_METHOD;
					}
				}
				
				
				List displayList = getMethodArgumentsList( classInfo.getName( ),
						methodInfo );
				for ( int i = 0; i < displayList.size( ); i++ )
				{
					String[] array = (String[]) displayList.get( i );
					createSubTreeItem( subItem,