Report that will list All test suite or test cases with Attachment on RQM 4.0
One answer
You may try <feedUrl>?fields=feed/entry/content/testcase/attachment to only list attachment of test cases. There is no filtering property for test cases/suites based on attachment. To find more about filtering properties, please go to https://jazz.net/wiki/bin/view/Main/RqmApi#fields. If the test cases with attachments have other features that can be filtered, you may used them as an alternative.