public EmailTemplateFileEntry setCategory(NotificationCategory category) {
        this.category = category;
        return this;
    }
Email template entry in the format stored in the template file index (notification-template-index).

@author Marc Savy {@literal <marc@blackparrotlabs.io>}
manager/api/rest-impl/src/main/java/io/apiman/manager/api/notifications/email/EmailTemplateFileEntry.java