Is there an API (Java/REST) through which I can reliably determine to which segments a given user belongs? I do not see an obvious way in the documented REST API, but curious if someone is aware of an approach that will work.
Thanks for reaching out. There isn't a way to get a list of segments that a user belongs to. However, you can use mboxTrace to get a better view of what's happening during testing. There is more information on mboxTrace here: https://marketing.adobe.com/resources/help/en_US/tnt/help/c_content_trouble.html