protected void ensureDeleteInAllServers(String blobId, MockServerLayout serverLayout) throws IOException {
    BlobId id = new BlobId(blobId, mockClusterMap);
    for (MockServer server : serverLayout.getMockServers()) {
      if (!server.getBlobs().get(blobId).isDeleted()) {
        DeleteRequest deleteRequest =
            new DeleteRequest(NonBlockingRouter.correlationIdGenerator.incrementAndGet(), routerConfig.routerHostname,
                id, mockTime.milliseconds());
        server.send(deleteRequest).release();
        deleteRequest.release();
      }
    }
  }
Ensure that Delete request for given blob is reaches to all the  mock servers in the {@link MockServerLayout}.
@param blobId The blob id of which Delete request will be created.
@param serverLayout The mock server layout.
@throws IOException
ambry-router/src/test/java/com/github/ambry/router/NonBlockingRouterTestBase.java