List customer groupsList customer groupsResponses200A collection of customer groups.Schema — OPTIONALResource object[] — OPTIONALThe resource on which the action was taken.CustomerGroupId int32 — OPTIONALThe unique identifier of the customer group.Name string — OPTIONALThe name of the customer group.DiscountPercentage int32 — OPTIONALCustomers in this group receive this discount percentage.Message string — OPTIONALA status message for the action taken.Details string[] — OPTIONALAny validation messages for the data on the current action.