Adding Custom Header to GraphQLHttpClient

Hi there:

I have got a GraphQL Client instance which is tying to call a GraphQL API endpoint. My code looks like below:

`var graphQLClient = new GraphQLHttpClient("https://abc.com/graphql", new NewtonsoftJsonSerializer());

var raceRequest = new GraphQLRequest {
Query = @"
query ($input: GetRaceResultsInput, $before: String, $after: String, $first: Int, $last: Int) {
getRaceResults(before: $before, after: $after, first: $first, last: $last, input: $input) {
edges {
cursor
node {
raceId
horses {
horseId
}
}
}
}
}"
};

var graphQLResponse = await graphQLClient.SendQueryAsync(raceRequest);`

RaceResult is of the format:
**public class RaceResult
{
public string Result { get; set; }
}**

When the SendQueryAsync is excuted, I get the following error:

**System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception.
System.ComponentModel.Win32Exception (0x80090326): The message received was unexpected or badly formatted.**

My request header in postman has got custom key value pair like **x-developer-secret** and I get the desired result. Is there anyway to add customer header before calling the API? I tried the following:

**graphQLClient.HttpClient.DefaultRequestHeaders.Add("Authorization", $"bearer abcsecret");**

However it didn't work. Any help would be appreciated.

Thanks