Custom Sitecore JSS GraphQL resolver

BaseGraphQLRenderingContentsResolver.cs

using Microsoft.Extensions.DependencyInjection;
using Newtonsoft.Json.Linq;
using Sitecore.JavaScriptServices.GraphQL.LayoutService;
using Sitecore.LayoutService.Configuration;
using Sitecore.LayoutService.ItemRendering.ContentsResolvers;
using Sitecore.Mvc.Presentation;
using System;

namespace Custom.Foundation.Content.JavascriptServices.RenderingContentsResolvers
{
    /// <summary>
    /// Add graphQL query data to the resolver data.
    /// </summary>
    /// <seealso cref="Sitecore.LayoutService.ItemRendering.ContentsResolvers.RenderingContentsResolver" />
    public class BaseGraphQLRenderingContentsResolver : RenderingContentsResolver
    {
        private readonly IServiceProvider serviceProvider;

        public BaseGraphQLRenderingContentsResolver(IServiceProvider serviceProvider)
        {
            this.serviceProvider = serviceProvider;
        }

        public override object ResolveContents(Rendering rendering, IRenderingConfiguration renderingConfig)
        {
            var contents = (JObject)base.ResolveContents(rendering, renderingConfig);

            var query = rendering.RenderingItem.InnerItem[Sitecore.JavaScriptServices.Core.FieldIDs.JsonRendering.GraphQLQuery];
            if (string.IsNullOrWhiteSpace(query))
            {
                return contents;
            }

            var graphqlResolver = ActivatorUtilities.GetServiceOrCreateInstance(serviceProvider, typeof(GraphQLAwareRenderingContentsResolver)) as IRenderingContentsResolver;
            contents["additionalData"] = (JObject)graphqlResolver.ResolveContents(rendering, renderingConfig);

            return contents;
        }
    }
}