目的のレプリゼンテーションのリクエスト

curl https://api.box.com/2.0/files/123?fields=representations \
    -H "x-rep-hints: [pdf]" \
    -H "authorization: Bearer ACCESS_TOKEN"

curl https://api.box.com/2.0/files/123?fields=representations \
    -H "x-rep-hints: [jpg?dimensions=94x94]" \
    -H "authorization: Bearer ACCESS_TOKEN"

curl https://api.box.com/2.0/files/123?fields=representations \
    -H "x-rep-hints: [pdf][jpg?dimensions=94x94]" \
    -H "authorization: Bearer ACCESS_TOKEN"

{
  "etag": "1",
  "id": "123",
  "representations": {
    "entries": [
      {
        "content": {
          "url_template": "https://dl.boxcloud.com/api/2.0/internal_files/123/versions/345/representations/pdf/content/{+asset_path}"
        },
        "info": {
          "url": "https://api.box.com/2.0/internal_files/123/versions/345/representations/pdf"
        },
        "properties": {},
        "representation": "pdf",
        "status": {
          "state": "success"
        }
      }
    ]
  },
  "type": "file"
}