CreditDocument management and related CreditDocument functions.

The following operations are supported. For a formal definition, please review the Service Description.

• CreateCredit
  Send an CreditDocument to the gateway
• GetCredit
  Retrieve a specific CreditDocument.
• GetCreditJSON
  Retrieve a specific CreditDocument.
• ListNewCredits
  All the credits that have not been collected by you
• MarkCreditAsReceived
  Requested date will be set for CreditDocument and CreditDocument will no longer be in 'New' list.