ValidateVisitor {

    {{
    private String errors = "";
    }}

    before apple {{
        if (host.get_weight() != null && host.get_weight().get_value() < 1)
            addError("Value (" + host.get_weight().get_value() + ") of element 'weight' is < 1");
    }}

    before orange {{
        if (host.get_weight() != null && host.get_weight().get_value() < 1)
            addError("Value (" + host.get_weight().get_value() + ") of element 'weight' is < 1");
    }}

    public String get_return_val() {{
        return errors;
    }}

    private void addError(String errorText) {{
        errors = errors + "\n" + errorText;
    }}

}  // end of class ValidateVisitor