My question is about google API for fetching googlegroups.com users

Question

What is the google API for fetching googlegroups.com users?

gapi.client.init({
          apiKey: API_KEY,
          clientId: CLIENT_ID,
          discoveryDocs: DISCOVERY_DOCS,
          scope: SCOPES
        })

My question is related to public googlegroups.com not related to Gsuite groups.