@Override
    public SwitchExpression convertChildren(ExpressionConverter converter) {
        var convertedCases = new LinkedHashMap<String, Expression>();
        for (var entry : cases.entrySet()) {
            var converted = converter.branch().convert(entry.getValue());
            if (converted != null)
                convertedCases.put(entry.getKey(), converted);
        }
        return new SwitchExpression(convertedCases, converter.branch().convert(defaultExp));
    }
The default expression, or null if none
indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/SwitchExpression.java