In Oracle Integration Generation 3, you can customize an integration in an accelerator project by adding and configuring an extension group, which is what enables the integration customization by adding to the integrations in your accelerator project invoke connections (stitch, for-each, switch, map), integration actions, and global variables.

For more details on how to perform these changes, refer to Manage a Project in Using Integrations in Oracle Integration 3, and to the Knowledge Base article How To Extend Oracle Integration Cloud Gen3 Project (Doc ID 3017378.1).