Parallel call to Elasticsearch in c# - elasticsearch

Question

I am trying to make a parallel call to Elasticsearch index for multiple queries and aggregate the result, using Parallel.ForEach.
My code:
private static List<SearchResponse<dynamic>> SearchQueryInParallel(string indexName, string lang, string[] eQueries)
{
var result = new List<SearchResponse<dynamic>>();
var exceptions = new ConcurrentQueue<Exception>();
object mutex = new object();
try
{
Parallel.ForEach(eQueries,
() => new SearchResponse<dynamic>()
, (q, loopState, subList) =>
{
var x = LowlevelClient.Search<SearchResponse<dynamic>>(indexName, $"article_{lang}", q);
subList = x;
return subList;
}, subList =>
{
lock (result)
result.Add(subList);
}
);
}
catch (AggregateException ae)
{
foreach (var e in ae.InnerExceptions)
{
exceptions.Enqueue(e);
}
}
if (exceptions.ToList().Any())
{
//there are exceptions, do something with them
//do something?
}
return result;
}
The problem I am facing is that sublist in the above case is long.
It gives me the following error:
Can not convert from SearchResponse to long.
The same thing is working when I used without multithreading, the code is:
var items = new List<dynamic>();
var searchResponse = lowLevelClient.Search<SearchResponse<dynamic>>(elasticIndexName, $"article_{languageCode.ToLowerInvariant()}", query);
foreach (var document in searchResponse.Body.Documents)
{
items.Add(document);
}
Any help, please? If somebody has any other way to achieve the parallel call and aggregating data from returned values would be greatly appreciated.