[DData config] Added reproduction

Directory.Build.props

@@ -13,7 +13,7 @@
     <PackageReadmeFile>README.md</PackageReadmeFile>
   </PropertyGroup>
   <PropertyGroup>
-    <LangVersion>10.0</LangVersion>
+    <LangVersion>12.0</LangVersion>
     <Nullable>enable</Nullable>
   </PropertyGroup>
   <PropertyGroup>

src/Akka.Cluster.Hosting.Tests/DDataOptionsSpecs.cs

@@ -0,0 +1,63 @@
+using System.Threading.Tasks;
+using Akka.Actor;
+using Akka.Cluster.Sharding;
+using Akka.DistributedData;
+using Akka.Hosting;
+using FluentAssertions;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Akka.Cluster.Hosting.Tests;
+
+public class DDataOptionsSpecs
+{
+    public DDataOptionsSpecs(ITestOutputHelper output)
+    {
+        Output = output;
+    }
+
+    public ITestOutputHelper Output { get; }
+
+    public static readonly TheoryData<DDataOptions> DDataOptionsTypes = new TheoryData<DDataOptions>()
+    {
+        new DDataOptions() // empty
+        {
+            Durable = new DurableOptions()
+            {
+                Keys = []
+            }
+        },
+        new DDataOptions() // null
+        {
+            Durable = new DurableOptions()
+            {
+                Keys = null
+            }
+        },
+    };
+
+    /// <summary>
+    /// Reproduction for https://github.com/akkadotnet/Akka.Hosting/issues/512 
+    /// </summary>
+    [Theory]
+    [MemberData(nameof(DDataOptionsTypes))]
+    public async Task Should_not_emit_durable_keys_when_empty(DDataOptions options)
+    {
+        // arrange
+        using var host = await TestHelper.CreateHost(builder =>
+            {
+                builder
+                    .WithDistributedData(options);
+            },
+            new ClusterOptions() { Roles = new[] { "my-host" } }, Output);
+
+        var actorSystem = host.Services.GetRequiredService<ActorSystem>();
+
+        // act
+        var ddataSettings = ReplicatorSettings.Create(actorSystem); // parse the settings
+
+        // assert
+        ddataSettings.DurableKeys.Should().BeEmpty();
+    }
+}

src/Directory.Build.props

@@ -0,0 +1,50 @@
+<Project>
+    <PropertyGroup>
+        <Copyright>Copyright © 2013-2023 Akka.NET Team</Copyright>
+        <Authors>Akka.NET Team</Authors>
+        <VersionPrefix>1.5.19</VersionPrefix>
+        <PackageReleaseNotes>• [Update Akka.NET to 1.5.19](https://github.com/akkadotnet/akka.net/releases/tag/1.5.19)</PackageReleaseNotes>
+        <PackageIcon>akkalogo.png</PackageIcon>
+        <PackageProjectUrl>
+            https://github.com/akkadotnet/Akka.Hosting
+        </PackageProjectUrl>
+        <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
+        <NoWarn>$(NoWarn);CS1591</NoWarn>
+        <PackageReadmeFile>README.md</PackageReadmeFile>
+    </PropertyGroup>
+
+    <PropertyGroup>
+        <LangVersion>12.0</LangVersion>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <PropertyGroup>
+        <LibraryFramework>netstandard2.0</LibraryFramework>
+        <TestsNetCoreFramework>net6.0</TestsNetCoreFramework>
+        <XunitVersion>2.8.1</XunitVersion>
+        <TestSdkVersion>17.11.1</TestSdkVersion>
+        <CoverletVersion>6.0.2</CoverletVersion>
+	    <XunitRunneVisualstudio>2.8.1</XunitRunneVisualstudio>
+        <AkkaVersion>1.5.30</AkkaVersion>
+        <MicrosoftExtensionsVersion>[6.0.0,)</MicrosoftExtensionsVersion>
+    </PropertyGroup>
+
+    <!-- SourceLink support for all Akka.NET projects -->
+    <ItemGroup>
+        <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <None Include="$(MSBuildThisFileDirectory)\..\docs\images\akkalogo.png" Pack="true" Visible="false" PackagePath="\" />
+        <None Include="$(MSBuildThisFileDirectory)\..\README.md" Pack="true" Visible="false" PackagePath="\" />
+    </ItemGroup>
+
+    <PropertyGroup>
+        <PublishRepositoryUrl>true</PublishRepositoryUrl>
+        <!-- Optional: Embed source files that are not tracked by the source control manager in the PDB -->
+        <EmbedUntrackedSources>true</EmbedUntrackedSources>
+        <!-- Optional: Build symbol package (.snupkg) to distribute the PDB containing Source Link -->
+        <IncludeSymbols>true</IncludeSymbols>
+        <SymbolPackageFormat>snupkg</SymbolPackageFormat>
+    </PropertyGroup>
+</Project>