Nullable reference type

src/Microsoft.Azure.AppConfiguration.AspNetCore/AzureAppConfigurationRefreshExtensions.cs

@@ -25,7 +25,7 @@ public static IApplicationBuilder UseAzureAppConfiguration(this IApplicationBuil
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            IConfigurationRefresherProvider refresherProvider = (IConfigurationRefresherProvider)builder.ApplicationServices.GetService(typeof(IConfigurationRefresherProvider));
+            IConfigurationRefresherProvider? refresherProvider = (IConfigurationRefresherProvider?)builder.ApplicationServices.GetService(typeof(IConfigurationRefresherProvider));
 
             // Verify if AddAzureAppConfiguration was done before calling UseAzureAppConfiguration.
             // We use the IConfigurationRefresherProvider to make sure if the required services were added.

src/Microsoft.Azure.AppConfiguration.AspNetCore/Microsoft.Azure.AppConfiguration.AspNetCore.csproj

@@ -3,6 +3,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <Description>Microsoft.Azure.AppConfiguration.AspNetCore allows developers to use Microsoft Azure App Configuration service as a configuration source in their applications. This package adds additional features for ASP.NET Core applications to the existing package Microsoft.Extensions.Configuration.AzureAppConfiguration.</Description>
     <SignAssembly>true</SignAssembly>
     <DelaySign>false</DelaySign>

src/Microsoft.Azure.AppConfiguration.Functions.Worker/AzureAppConfigurationRefreshExtensions.cs

@@ -24,7 +24,7 @@ public static class AzureAppConfigurationRefreshExtensions
         public static IFunctionsWorkerApplicationBuilder UseAzureAppConfiguration(this IFunctionsWorkerApplicationBuilder builder)
         {
             IServiceProvider serviceProvider = builder.Services.BuildServiceProvider();
-            IConfigurationRefresherProvider refresherProvider = serviceProvider.GetService<IConfigurationRefresherProvider>();
+            IConfigurationRefresherProvider? refresherProvider = serviceProvider.GetService<IConfigurationRefresherProvider>();
 
             // Verify if AddAzureAppConfiguration was done before calling UseAzureAppConfiguration.
             // We use the IConfigurationRefresherProvider to make sure if the required services were added.

src/Microsoft.Azure.AppConfiguration.Functions.Worker/Microsoft.Azure.AppConfiguration.Functions.Worker.csproj

@@ -3,6 +3,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <Description>Microsoft.Azure.AppConfiguration.Functions.Worker allows developers to use the Microsoft Azure App Configuration service as a configuration source in their applications. This package adds additional features to the existing package Microsoft.Extensions.Configuration.AzureAppConfiguration for .NET Azure Functions running in an isolated process.</Description>
     <SignAssembly>true</SignAssembly>
     <DelaySign>false</DelaySign>

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationKeyVaultOptions.cs

@@ -18,15 +18,15 @@ public class AzureAppConfigurationKeyVaultOptions
         // This allows the provider to throw a KeyVaultReferenceException with all relevant information and halt startup instead of timing out.
         private const int KeyVaultMaxRetries = 6;
 
-        internal TokenCredential Credential;
+        internal TokenCredential? Credential;
         internal SecretClientOptions ClientOptions = new SecretClientOptions
         {
             Retry = {
                 MaxRetries = KeyVaultMaxRetries
             }
         };
         internal List<SecretClient> SecretClients = new List<SecretClient>();
-        internal Func<Uri, ValueTask<string>> SecretResolver;
+        internal Func<Uri, ValueTask<string>>? SecretResolver;
         internal Dictionary<string, TimeSpan> SecretRefreshIntervals = new Dictionary<string, TimeSpan>();
         internal TimeSpan? DefaultSecretRefreshInterval = null;
         internal bool IsKeyVaultRefreshConfigured = false;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationOptions.cs

@@ -51,19 +51,19 @@ public class AzureAppConfigurationOptions
         /// <summary>
         /// The list of connection strings used to connect to an Azure App Configuration store and its replicas.
         /// </summary>
-        internal IEnumerable<string> ConnectionStrings { get; private set; }
+        internal IEnumerable<string>? ConnectionStrings { get; private set; }
 
         /// <summary>
         /// The list of endpoints of an Azure App Configuration store.
         /// If this property is set, the <see cref="Credential"/> property also needs to be set.
         /// </summary>
-        internal IEnumerable<Uri> Endpoints { get; private set; }
+        internal IEnumerable<Uri>? Endpoints { get; private set; }
 
         /// <summary>
         /// The credential used to connect to the Azure App Configuration.
         /// If this property is set, the <see cref="Endpoints"/> property also needs to be set.
         /// </summary>
-        internal TokenCredential Credential { get; private set; }
+        internal TokenCredential? Credential { get; private set; }
 
         /// <summary>
         /// A collection of <see cref="KeyValueSelector"/> specified by user.
@@ -96,7 +96,7 @@ public class AzureAppConfigurationOptions
         internal IEnumerable<IKeyValueAdapter> Adapters
         {
             get => _adapters;
-            set => _adapters = value?.ToList();
+            set => _adapters = value?.ToList() ?? new List<IKeyValueAdapter>();
         }
 
         /// <summary>
@@ -112,17 +112,17 @@ internal IEnumerable<IKeyValueAdapter> Adapters
         /// <summary>
         /// For use in tests only. An optional configuration client manager that can be used to provide clients to communicate with Azure App Configuration.
         /// </summary>
-        internal IConfigurationClientManager ClientManager { get; set; }
+        internal IConfigurationClientManager? ClientManager { get; set; }
 
         /// <summary>
         /// For use in tests only. An optional class used to process pageable results from Azure App Configuration.
         /// </summary>
-        internal IConfigurationSettingPageIterator ConfigurationSettingPageIterator { get; set; }
+        internal IConfigurationSettingPageIterator? ConfigurationSettingPageIterator { get; set; }
 
         /// <summary>
         /// For use in tests only. An optional activity source name to specify the activity source used by the configuration provider.
         /// </summary>
-        internal string ActivitySourceName { get; set; }
+        internal string? ActivitySourceName { get; set; }
 
         /// <summary>
         /// An optional timespan value to set the minimum backoff duration to a value other than the default.
@@ -157,7 +157,7 @@ internal IEnumerable<IKeyValueAdapter> Adapters
         /// <summary>
         /// Client factory that is responsible for creating instances of ConfigurationClient.
         /// </summary>
-        internal IAzureClientFactory<ConfigurationClient> ClientFactory { get; private set; }
+        internal IAzureClientFactory<ConfigurationClient>? ClientFactory { get; private set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AzureAppConfigurationOptions"/> class.
@@ -215,7 +215,7 @@ public AzureAppConfigurationOptions SetClientFactory(IAzureClientFactory<Configu
         /// The characters asterisk (*), comma (,) and backslash (\) are reserved and must be escaped using a backslash (\).
         /// Up to 5 tag filters can be provided. If no tag filters are provided, key-values will not be filtered based on tags.
         /// </param>
-        public AzureAppConfigurationOptions Select(string keyFilter, string labelFilter = LabelFilter.Null, IEnumerable<string> tagFilters = null)
+        public AzureAppConfigurationOptions Select(string keyFilter, string labelFilter = LabelFilter.Null, IEnumerable<string>? tagFilters = null)
         {
             if (string.IsNullOrEmpty(keyFilter))
             {

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure;
 using Azure.Data.AppConfiguration;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.SnapshotReference;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationSource.cs

@@ -28,7 +28,7 @@ public AzureAppConfigurationSource(Action<AzureAppConfigurationOptions> optionsI
 
         public IConfigurationProvider Build(IConfigurationBuilder builder)
         {
-            IConfigurationProvider provider = null;
+            IConfigurationProvider? provider = null;
 
             try
             {

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultKeyValueAdapter.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure;
 using Azure.Data.AppConfiguration;
 using Azure.Security.KeyVault.Secrets;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/AzureKeyVaultSecretProvider.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure.Security.KeyVault.Secrets;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions;
 using System;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureKeyVaultReference/CachedKeyVaultSecret.cs

@@ -10,7 +10,7 @@ internal class CachedKeyVaultSecret
         ///// <summary>
         ///// The value of the Key Vault secret.
         ///// </summary>
-        public string SecretValue { get; set; }
+        public string? SecretValue { get; set; }
 
         /// <summary>
         /// The time when this secret should be reloaded from Key Vault.
@@ -30,9 +30,9 @@ internal class CachedKeyVaultSecret
         /// <summary>
         /// The source <see cref="Uri"/> for this secret.
         /// </summary>
-        public Uri SourceId { get; }
+        public Uri? SourceId { get; }
 
-        public CachedKeyVaultSecret(string secretValue = null, Uri sourceId = null, DateTimeOffset? refreshAt = null, int refreshAttempts = 0)
+        public CachedKeyVaultSecret(string? secretValue = null, Uri? sourceId = null, DateTimeOffset? refreshAt = null, int refreshAttempts = 0)
         {
             SecretValue = secretValue;
             RefreshAt = refreshAt;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/ConfigurationClientManager.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 
 using Azure.Data.AppConfiguration;
 using DnsClient;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/EndpointComparer.cs

@@ -8,7 +8,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
 {
     internal class EndpointComparer : IEqualityComparer<Uri>
     {
-        public bool Equals(Uri endpoint1, Uri endpoint2)
+        public bool Equals(Uri? endpoint1, Uri? endpoint2)
         {
             return Uri.Compare(endpoint1,
                                endpoint2,

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Exceptions/KeyVaultReferenceException.cs

@@ -34,26 +34,26 @@ public KeyVaultReferenceException(string message,
         /// <summary>
         /// The key of the Key Vault reference that caused the exception.
         /// </summary>
-        public string Key { get; set; }
+        public string? Key { get; set; }
 
         /// <summary>
         /// The label of the Key Vault reference that caused the exception.
         /// </summary>
-        public string Label { get; set; }
+        public string? Label { get; set; }
 
         /// <summary>
         /// The etag of the Key Vault reference that caused the exception.
         /// </summary>
-        public string Etag { get; set; }
+        public string? Etag { get; set; }
 
         /// <summary>
         /// The secret identifier used by the Azure Key Vault reference that caused the exception.
         /// </summary>
-        public string SecretIdentifier { get; set; }
+        public string? SecretIdentifier { get; set; }
 
         /// <summary>
         /// The error code, if available, describing the cause of the exception. 
         /// </summary>
-        public string ErrorCode { get; set; }
+        public string? ErrorCode { get; set; }
     }
 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/EventGridEventExtensions.cs

@@ -20,7 +20,7 @@ public static class EventGridEventExtensions
         /// <param name="eventGridEvent"> EventGridEvent from EventGrid</param>
         /// <param name="pushNotification"> If this method returns true, the pushNotification  object contains details populated from eventGridEvent. If this method returns false, the pushNotification object is null. </param>
         /// <returns></returns>
-        public static bool TryCreatePushNotification(this EventGridEvent eventGridEvent, out PushNotification pushNotification)
+        public static bool TryCreatePushNotification(this EventGridEvent eventGridEvent, out PushNotification? pushNotification)
         {
             pushNotification = null;
 
@@ -29,9 +29,9 @@ public static bool TryCreatePushNotification(this EventGridEvent eventGridEvent,
                 return false;
             }
 
-            if (Uri.TryCreate(eventGridEvent.Subject, UriKind.Absolute, out Uri resourceUri))
+            if (Uri.TryCreate(eventGridEvent.Subject, UriKind.Absolute, out Uri? resourceUri))
             {
-                string syncToken = null;
+                string? syncToken = null;
 
                 try
                 {

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/StringExtensions.cs

@@ -8,7 +8,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions
 {
     internal static class StringExtensions
     {
-        public static bool TryParseContentType(this string contentTypeString, out ContentType contentType)
+        public static bool TryParseContentType(this string contentTypeString, out ContentType? contentType)
         {
             contentType = null;
 
@@ -35,7 +35,7 @@ public static bool TryParseContentType(this string contentTypeString, out Conten
             }
         }
 
-        public static string NormalizeNull(this string s)
+        public static string? NormalizeNull(this string? s)
         {
             return s == LabelFilter.Null ? null : s;
         }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/ClientFilter.cs

@@ -7,7 +7,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class ClientFilter
     {
-        public string Name { get; set; }
+        public string Name { get; set; } = string.Empty;
 
         public JsonElement Parameters { get; set; }
     }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureAllocation.cs

@@ -7,16 +7,16 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureAllocation
     {
-        public string DefaultWhenDisabled { get; set; }
+        public string? DefaultWhenDisabled { get; set; }
 
-        public string DefaultWhenEnabled { get; set; }
+        public string? DefaultWhenEnabled { get; set; }
 
-        public IEnumerable<FeatureUserAllocation> User { get; set; }
+        public IEnumerable<FeatureUserAllocation>? User { get; set; }
 
-        public IEnumerable<FeatureGroupAllocation> Group { get; set; }
+        public IEnumerable<FeatureGroupAllocation>? Group { get; set; }
 
-        public IEnumerable<FeaturePercentileAllocation> Percentile { get; set; }
+        public IEnumerable<FeaturePercentileAllocation>? Percentile { get; set; }
 
-        public string Seed { get; set; }
+        public string? Seed { get; set; }
     }
 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureConditions.cs

@@ -9,6 +9,6 @@ internal class FeatureConditions
     {
         public List<ClientFilter> ClientFilters { get; set; } = new List<ClientFilter>();
 
-        public string RequirementType { get; set; }
+        public string? RequirementType { get; set; }
     }
 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlag.cs

@@ -7,16 +7,16 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureFlag
     {
-        public string Id { get; set; }
+        public string Id { get; set; } = string.Empty;
 
         public bool Enabled { get; set; }
 
-        public FeatureConditions Conditions { get; set; }
+        public FeatureConditions? Conditions { get; set; }
 
-        public IEnumerable<FeatureVariant> Variants { get; set; }
+        public IEnumerable<FeatureVariant>? Variants { get; set; }
 
-        public FeatureAllocation Allocation { get; set; }
+        public FeatureAllocation? Allocation { get; set; }
 
-        public FeatureTelemetry Telemetry { get; set; }
+        public FeatureTelemetry? Telemetry { get; set; }
     }
 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureFlagOptions.cs

@@ -33,7 +33,7 @@ internal TimeSpan RefreshInterval
         /// <summary>
         /// The label that feature flags will be selected from.
         /// </summary>
-        public string Label { get; set; }
+        public string? Label { get; set; }
 
         /// <summary>
         /// The time after which the cached values of the feature flags expire.  Must be greater than or equal to 1 second.
@@ -81,7 +81,7 @@ public FeatureFlagOptions SetRefreshInterval(TimeSpan refreshInterval)
         /// The characters asterisk (*), comma (,) and backslash (\) are reserved and must be escaped using a backslash (\).
         /// Up to 5 tag filters can be provided. If no tag filters are provided, feature flags will not be filtered based on tags.
         /// </param>
-        public FeatureFlagOptions Select(string featureFlagFilter, string labelFilter = LabelFilter.Null, IEnumerable<string> tagFilters = null)
+        public FeatureFlagOptions Select(string featureFlagFilter, string labelFilter = LabelFilter.Null, IEnumerable<string>? tagFilters = null)
         {
             if (string.IsNullOrEmpty(featureFlagFilter))
             {

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureGroupAllocation.cs

@@ -7,8 +7,8 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureGroupAllocation
     {
-        public string Variant { get; set; }
+        public string? Variant { get; set; }
 
-        public IEnumerable<string> Groups { get; set; }
+        public IEnumerable<string>? Groups { get; set; }
     }
 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureManagementKeyValueAdapter.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+#nullable disable
 using Azure.Data.AppConfiguration;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions;
 using System;

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeaturePercentileAllocation.cs

@@ -6,7 +6,7 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeaturePercentileAllocation
     {
-        public string Variant { get; set; }
+        public string? Variant { get; set; }
 
         public double From { get; set; }
 

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureTelemetry.cs

@@ -10,6 +10,6 @@ internal class FeatureTelemetry
     {
         public bool Enabled { get; set; }
 
-        public IDictionary<string, string> Metadata { get; set; }
+        public IDictionary<string, string>? Metadata { get; set; }
     }
 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureUserAllocation.cs

@@ -7,8 +7,8 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureUserAllocation
     {
-        public string Variant { get; set; }
+        public string? Variant { get; set; }
 
-        public IEnumerable<string> Users { get; set; }
+        public IEnumerable<string>? Users { get; set; }
     }
 }