protected static String getBlobId(RestRequest restRequest) {
    String path = restRequest.getPath();
    return path.startsWith("/") ? path.substring(1) : path;
  }
Determines the blob ID desired by the request.
@param restRequest a {@link RestRequest} that represents the request.
@return the blob ID desired by the request.
ambry-api/src/test/java/com/github/ambry/rest/MockRestRequestService.java