Remove default JsonSerializer and require explicit configuration

[joerneu]

This line always overwrites Option.JsonSerializer:

graphql-client/src/GraphQL.Client/GraphQLHttpClient.cs

Line 57 in a727000

Options.JsonSerializer = serializer ?? throw new ArgumentNullException(nameof(serializer));

Therefore the following code does not work as expected:

_client = new GraphQLHttpClient(o =>
{
    o.EndPoint = new Uri(_testUrl);
    o.JsonSerializer = new SystemTextJsonSerializer(
        options =>
        {
            options.Converters.Add(new JsonStringEnumConverter());
        });
});

The constructor above calls the constructor

graphql-client/src/GraphQL.Client/GraphQLHttpClient.cs

Line 53 in a727000

public GraphQLHttpClient(GraphQLHttpClientOptions options, HttpClient httpClient) : this(options, httpClient, new NewtonsoftJsonSerializer()) { }

which sets the JsonSerializer always to NewtonsoftJsonSerializer.

By the way, I think it would be better to make a breaking change, remove the reference to GraphQL.Client.Serializer.Newtonsoft and require the caller to provide the serializer.

[sungam3r]

By the way, I think it would be better to make a breaking change, remove the reference to GraphQL.Client.Serializer.Newtonsoft and require the caller to provide the serializer.

Agree.

[rose-a]

Yeah you're right, I guess there should be only one "source of truth"...