Add business logic to a stub on the Activity page within the Events tab. Choose Business Logic in the Event Activity option. If you choose Business Logic, you can add a Pass Through action to define explicit pass-through behaviour that must be executed depending on the logic added to the stub.
For example, if a received message contains data that matches a particular condition, the configured Pass Through action could generate an error. Alternatively, the action could be configured to discard the message or to let the message pass through to the system under test (the possible actions depend on the transport being used).
For more information, see Activity tab.