...
Alternatively to the above approach, you can also attach extension sequences to an API using the API Publisher Web interface at the time the API is created. Log in to the API Publisher (https://localhost:9443/publisher) and click Add from the left panel. In the Add New API page that opens, navigate down to the Manage section where you find the Sequences section. There, you can select In/Out /Fault sequences for the API from the drop-down lists. For example,
To populate these drop-down lists, you must add mediation sequences as explained in the beginning.
...