One of the "out of the box" Service Offerings in CA Service Catalog is "Report an Issue". This is used for example in Unified Self Service to raise incidents in CA Service Desk Manager. If I wish to customize what happens when the service is requested, where is the action that triggers the creation of the Service Desk incident?
If you go to Home > Administration > Events-Rules-Actions > Request/Subscription Item Change > When Category is Service Management Content and Status is Pending Fulfillment > Create Incident you'll find the Java action that performs this. There you'll be able to disable the action, or add a different one if you require.