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
}
		if ( filter( TREE_NAME_PARAMETERS, filterList ) )
		{
			createParamtersTree( );
		}
		if ( filter( TREE_NAME_NATIVE_OBJECTS, filterList ) )
		{
			createNativeObjectsTree( );
		}
		if ( filter( TREE_NAME_BIRT_OBJECTS, filterList ) )
		{
			createBirtObjectsTree( );
		}
		if ( filter( TREE_NAME_OPERATORS, filterList ) )
		{
			createOperatorsTree( );
		}
	}
	/**
	 * Filters the tree name, given the filter list.
	 * 
	 * @param treeName
	 *            the tree name to be filtered.
	 * @param filters
	 *            the filter list.
	 * @return true if the tree name passes the filter list.
	 */
	private boolean filter( String treeName, List filters )
	{
		if ( filters == null )