Where is the submissions list in challenge api

[SarahRuan]

Hi team, I'm working on a academic research on crowdsourcing and is using your public api to gather some data. Just want to know that in V5 challenge API https://api.topcoder.com/v5/challenges/?status=Completed how can I get the list of submissions' handles? This field was available in frontend app can show the submission' list but I can't find any api call that contains the JSON data of submissions list.How can I gather the submissions list?

Thank you for your help