curl -i -X GET "https://api.box.com/2.0/retention_policies/982312/assignments" \
     -H "authorization: Bearer <ACCESS_TOKEN>"

{
  "entries": [
    {
      "id": "11446498",
      "type": "retention_policy_assignment",
      "retention_policy": {
        "id": "12345",
        "type": "retention_policy",
        "policy_name": "Some Policy Name",
        "retention_length": "365",
        "disposition_action": "permanently_delete",
        "max_extension_length": "365"
      },
      "assigned_to": {
        "id": "a983f69f-e85f-4ph4-9f46-4afdf9c1af65",
        "type": "metadata_template"
      },
      "filter_fields": [
        {
          "field": "a0f4ee4e-1dc1-4h90-a8a9-aef55fc681d4",
          "value": "0c27b756-0p87-4fe0-a43a-59fb661ccc4e"
        }
      ],
      "assigned_by": {
        "id": "11446498",
        "type": "user",
        "name": "Aaron Levie",
        "login": "ceo@example.com"
      },
      "assigned_at": "2012-12-12T10:53:43-08:00",
      "start_date_field": "upload_date"
    }
  ],
  "limit": 1000,
  "next_marker": "JV9IRGZmieiBasejOG9yDCRNgd2ymoZIbjsxbJMjIs3kioVii"
}