@Override
  public void handleGet(RestRequest restRequest, RestResponseChannel restResponseChannel) {
    if (shouldProceed(restRequest, restResponseChannel)) {
      String blobId = getBlobId(restRequest);
      MockGetCallback callback = new MockGetCallback(this, restRequest, restResponseChannel);
      router.getBlob(blobId, new GetBlobOptionsBuilder().operationType(GetBlobOptions.OperationType.All).build(),
          callback, null);
    }
  }
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