Just in case you are looking for the same requirement as I do, please have a look at the below idea which explains why there is no subject area available for Collections. If you have the same requirement, please vote for the below idea.
https://community.oracle.com/customerconnect/discussion/486502/otbi-subject-area-for-advanced-collections#latest
https://community.oracle.com/customerconnect/discussion/486502/otbi-subject-area-for-advanced-collections#latest
