Enable nullable on HealthChecks.EntityFrameworkCore (#28815)

Author: JamesNK

src/Middleware/HealthChecks.EntityFrameworkCore/src/DbContextHealthCheckOptions.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -10,6 +10,6 @@ namespace Microsoft.Extensions.Diagnostics.HealthChecks
 {
     internal sealed class DbContextHealthCheckOptions<TContext> where TContext : DbContext
     {
-        public Func<TContext, CancellationToken, Task<bool>> CustomTestQuery { get; set; }
+        public Func<TContext, CancellationToken, Task<bool>>? CustomTestQuery { get; set; }
     }
 }

src/Middleware/HealthChecks.EntityFrameworkCore/src/DependencyInjection/EntityFrameworkCoreHealthChecksBuilderExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.EntityFrameworkCore;
@@ -54,10 +55,10 @@ public static class EntityFrameworkCoreHealthChecksBuilderExtensions
         /// </remarks>
         public static IHealthChecksBuilder AddDbContextCheck<TContext>(
             this IHealthChecksBuilder builder,
-            string name  = null,
+            string? name  = null,
             HealthStatus? failureStatus = default,
-            IEnumerable<string> tags = default,
-            Func<TContext, CancellationToken, Task<bool>> customTestQuery = default)
+            IEnumerable<string>? tags = default,
+            Func<TContext, CancellationToken, Task<bool>>? customTestQuery = default)
             where TContext : DbContext
         {
             if (builder == null)
@@ -75,7 +76,7 @@ public static IHealthChecksBuilder AddDbContextCheck<TContext>(
                 builder.Services.Configure<DbContextHealthCheckOptions<TContext>>(name, options => options.CustomTestQuery = customTestQuery);
             }
 
-            return builder.AddCheck<DbContextHealthCheck<TContext>>(name, failureStatus, tags);
+            return builder.AddCheck<DbContextHealthCheck<TContext>>(name, failureStatus, tags ?? Enumerable.Empty<string>());
         }
     }
 }

src/Middleware/HealthChecks.EntityFrameworkCore/src/Microsoft.Extensions.Diagnostics.HealthChecks.EntityFrameworkCore.csproj

@@ -8,6 +8,7 @@
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>diagnostics;healthchecks;entityframeworkcore</PackageTags>
     <BaseNamespace>Microsoft.Extensions.Diagnostics.HealthChecks</BaseNamespace>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>

src/Middleware/HealthChecks.EntityFrameworkCore/src/PublicAPI.Shipped.txt

@@ -1,3 +1,3 @@
 #nullable enable
 Microsoft.Extensions.DependencyInjection.EntityFrameworkCoreHealthChecksBuilderExtensions
-~static Microsoft.Extensions.DependencyInjection.EntityFrameworkCoreHealthChecksBuilderExtensions.AddDbContextCheck<TContext>(this Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder builder, string name = null, Microsoft.Extensions.Diagnostics.HealthChecks.HealthStatus? failureStatus = null, System.Collections.Generic.IEnumerable<string> tags = null, System.Func<TContext, System.Threading.CancellationToken, System.Threading.Tasks.Task<bool>> customTestQuery = null) -> Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder
+static Microsoft.Extensions.DependencyInjection.EntityFrameworkCoreHealthChecksBuilderExtensions.AddDbContextCheck<TContext>(this Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder! builder, string? name = null, Microsoft.Extensions.Diagnostics.HealthChecks.HealthStatus? failureStatus = null, System.Collections.Generic.IEnumerable<string!>? tags = null, System.Func<TContext!, System.Threading.CancellationToken, System.Threading.Tasks.Task<bool>!>? customTestQuery = null) -> Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder!