Provoking non-encoding av NameValueKey pairs in HttpClient with diagnostics

csproj with 2.2. dependencies

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework> <!-- Switch this to 3.0 and everything works fine -->

    <IsPackable>false</IsPackable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="2.2.0" />
    <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.8.0" />

    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.2.0" />
    <PackageReference Include="xunit" Version="2.4.0" />
    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.0" />
    <PackageReference Include="coverlet.collector" Version="1.0.1" />
  </ItemGroup>

</Project>

Test case

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.TestHost;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.Diagnostics;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using Xunit;

namespace BlobingTest
{
    public class CorrelationContextTests : IClassFixture<TestServerFixture>
    {
        public CorrelationContextTests(TestServerFixture fixture)
        {
            Fixture = fixture;
        }

        protected TestServerFixture Fixture { get; }

        [Fact]
        public async Task When_InvalidCharacterInCorrelationContext_ItShould_Throw()
        {
            // Arrange
            var client = new HttpClient();
            var activity = new Activity("gary");

            // Act
            activity.AddBaggage("Correlation-Context", "matthew@gmail.com");
            activity.Start();
            var response = await client.GetAsync("http://www.google.com");
            activity.Stop();

            // Assert
            Assert.True(response.StatusCode == HttpStatusCode.OK);
        }
    }

    public class TestServerFixture : IDisposable
    {
        public TestServerFixture()
        {
            Server = new TestServer(
                new WebHostBuilder()
                    .UseStartup<FakeStartUp>()
            );
        }

        public void Dispose()
        {
            // ... clean up
            Server.Dispose();
        }

        public TestServer Server { get; private set; }
    }

    public class FakeStartUp
    {
        public virtual void ConfigureServices(IServiceCollection services)
        {
            services.AddApplicationInsightsTelemetry(options =>
            {
                options.InstrumentationKey = "<secret key>";
            });
        }

        public virtual void Configure(IApplicationBuilder app)
        {
        }
    }
}