Payment group type configuration is defined using the atg.commerce.csr.order.
PaymentGroupTypeConfiguration class. The class contains the following:

atg.commerce.csr.order.PaymentGroupTypeConfiguration extends
  atg.commerce.csr.order.CommerceTypeConfiguration
  protected PageFragment mEditRefundMethodPageFragment;
  protected PageFragment mDisplayRefundMethodPageFragment;
  mEditRefundMethodPageFragmentTitleKey;

The PaymentGroupTypeConfiguration class configures the payment group and refund methods. The base class properties configure the payment group. The refund methods are used for the returns and exchange pages. For detailed information on the PaymentGroupTypeConfiguration class, refer to the ATG API Reference for Commerce Service Center.

Payment group types are provided in these locations:

There are five default payment group types: Credit Card, Store Credit, Gift Certificate, PayInStore and Cash. These are defined in the SupportedPaymentGroupTypes property of the CSRConfigurator. If an order contains a payment group type that is not listed, the order will not be loaded.

Note: Commerce Service Center does not support or display Commerce B2B payment group types. Because Commerce Service Center runs orders through multiple validations, customizations made to support B2B payment group types, such as B2B Approvals, may generate errors.