public override async Task <bool> ExistsAsync(CancellationToken cancellationToken)
{
// Create the request.
IIndexExistsRequest request = new IndexExistsDescriptor(Indices.Index <T>());
// Get the response.
IExistsResponse response = await ElasticClient.IndexExistsAsync(request, cancellationToken)
.ConfigureAwait(false);
// Throw if invalid.
response.ThrowIfError();
// Return the response.
return(response.Exists);
}