Return an array where each entry is an object with this form:

{ source: "fitbit", name: "Fitbit", usernames: ["beau", "madprime"] }

GET /api/public-data/members-by-source/?format=api&source=direct-sharing-468
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Cache-Control: max-age=0, no-cache, no-store, must-revalidate
Content-Type: application/json
Expires: Wed, 21 Oct 2020 11:13:34 GMT
Vary: Accept

{
    "count": 50,
    "next": null,
    "previous": null,
    "results": [
        {
            "source": "direct-sharing-468",
            "name": "OPEN",
            "usernames": [
                "gedankenstuecke",
                "stephenbrad",
                "246PWD",
                "dramageek",
                "Lilly",
                "zreptil",
                "MarcelZ",
                "cascer1",
                "clehner1961",
                "swissalpine",
                "Unidragon",
                "AndyS",
                "Shaggydog",
                "steffen",
                "Zuckerschule",
                "Jarvis532",
                "friendocrino",
                "k1232",
                "Gosee1960",
                "cristinav",
                "Ludovik95",
                "No_one_20",
                "Shane",
                "chrisgruebl",
                "RalfCGM",
                "Lew_Easy",
                "Pumpit",
                "guydavies",
                "Rachel162",
                "reimarmetzen",
                "Lispro",
                "RandomLuck",
                "MarkOldham",
                "Rainforest",
                "CGinDC",
                "jonprogers",
                "aholareijo",
                "ShivGaff",
                "kerray",
                "Alice",
                "lopep",
                "ansku",
                "avitabile",
                "mohuma",
                "Cleo2014",
                "anirudhreddy28",
                "Jelmer",
                "HermannW",
                "Tanja3981",
                "Kz9Fl",
                "thseliger",
                "28021990",
                "Heiner1",
                "Tycho",
                "an_di",
                "hise002",
                "DarthDadT1D",
                "Maren",
                "cjlogan",
                "Atze6r",
                "lisa675",
                "Dragan",
                "Waldkauz",
                "PeterLeimbach",
                "Unterstark",
                "paulplant",
                "dascheberg",
                "MTR",
                "Mausd33",
                "winni67",
                "elliroux",
                "Binja65"
            ]
        }
    ]
}