private static void ValidateDocumentTemplate(DocumentTemplate documentTemplate)
        {
            var fieldsInBody = Regex.Matches(documentTemplate.Body + " ", @"\$(\S+)\$");

            foreach (var bodyField in fieldsInBody)
            {
                var bodyFieldName = bodyField.ToString();
                if (documentTemplate.GetAllowedFieldsWithDelimeters().All(p => p != bodyFieldName))
                {
                    throw new BusinessRuleException("Body", string.Format(
                                                        "The field {0} is not in the allowable list of fields for this template",
                                                        bodyFieldName));
                }
            }
        }