close
The close method is called to clean up resources that are held by the Transaction object. It shall be called when the transaction is completed. Note: This method is required to be called only when the doChallenge method is not called in the transaction. The following are some examples of scenarios in which the close method is called:
Frictionless transaction.
The ACS recommends a challenge, but the Merchant overrides the recommendation and chooses to complete the transaction without a challenge.