public void handle(RestRequest restRequest, RestResponseChannel restResponseChannel, Callback<Void> callback)
      throws RestServiceException {
    // named blob requests have their account/container in the URI, so checks can be done prior to ID conversion.
    if (getRequestPath(restRequest).matchesOperation(Operations.NAMED_BLOB)) {
      accountAndContainerInjector.injectAccountContainerForNamedBlob(restRequest, metrics.headBlobMetricsGroup);
    }
    new CallbackChain(restRequest, restResponseChannel, callback).start();
  }
Handler to handle all the http HEAD requests on blobs.
ambry-frontend/src/main/java/com/github/ambry/frontend/HeadBlobHandler.java