Without limiting the generality of the oath set out in Code Section 15-16-4, it shall be a violation of a sheriff's oath of office for any sheriff to engage either directly or indirectly in a private security, private investigation, bail bonding, or wrecker towing business in the county in which the sheriff has jurisdiction. As used in this Code section, "engaging indirectly" in such a business shall include the engagement in a prohibited business by the spouse or an unemancipated child of a sheriff.