Merge branch 'dev' into connection-status-feature

docs/en/Module-Development-Basics.md

@@ -147,7 +147,7 @@ Lastly, you can override ``OnApplicationShutdown`` method if you want to execute
 
 ## Module Dependencies
 
-In a modular application, it's not unusual for one module to depend upon another module(s). An Abp module must declare ``[DependsOn]`` attribute if it does have a dependency upon another module, as shown below:
+In a modular application, it's not unusual for one module to depend upon another module(s). An ABP module must declare a ``[DependsOn]`` attribute if it does have a dependency upon another module, as shown below:
 
 ````C#
 [DependsOn(typeof(AbpAspNetCoreMvcModule))]
@@ -162,6 +162,27 @@ You can use multiple ``DependsOn`` attribute or pass multiple module types to a
 
 A depended module may depend on another module, but you only need to define your direct dependencies. ABP investigates the dependency graph for the application at startup and initializes/shutdowns modules in the correct order.
 
+## Additional Module Assemblies
+
+ABP automatically registers all the services of your module to the [dependency injection](Dependency-Injection.md) system. It finds the service types by scanning types in the assembly that defines your module class. That assembly is considered as the main assembly of your module.
+
+Typically, every assembly contains a separate module class definition. Then modules depend on each other using the `DependsOn` attribute as explained in the previous section. However, in some rare cases, your module may consist of multiple assemblies, and only one of them defines a module class, and you want to make the other assemblies parts of your module. In that case, you can use the `AdditionalAssembly` attribute as shown below:
+
+````csharp
+[DependsOn(...)] // Your module dependencies as you normally do
+[AdditionalAssembly(typeof(BlogService))] // A type in the target assembly
+public class BlogModule
+{
+    //...
+}
+````
+
+In this example, we assume that the `BlogService` class is inside one assembly (`csproj`) and the `BlogModule` class is inside another assembly (`csproj`). With the `AdditionalAssembly` definition, ABP will load the assembly containing the `BlogService` class as a part of the blog module.
+
+Notice that `BlogService` is only an arbitrary selected type in the target assembly. It is just used to indicate the related assembly. You could use any type in the assembly.
+
+> WARNING: If you need to use the `AdditionalAssembly`, be sure that you don't design your system in a wrong way. With this example above, the `BlogService` class' assembly should normally have its own module class and the `BlogModule` should depend on it using the `DependsOn` attribute. Do not use the `AdditionalAssembly` attribute when you can already use the `DependsOn` attribute.
+
 ## Framework Modules vs Application Modules
 
 There are **two types of modules.** They don't have any structural difference but categorized by functionality and purpose:

framework/src/Volo.Abp.ApiVersioning.Abstractions/Volo.Abp.ApiVersioning.Abstractions.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.ApiVersioning.Abstractions</AssemblyName>
     <PackageId>Volo.Abp.ApiVersioning.Abstractions</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.ApiVersioning.Abstractions/Volo/Abp/ApiVersioning/IRequestedApiVersion.cs

@@ -2,5 +2,5 @@
 
 public interface IRequestedApiVersion
 {
-    string Current { get; }
+    string? Current { get; }
 }

framework/src/Volo.Abp.ApiVersioning.Abstractions/Volo/Abp/ApiVersioning/NullRequestedApiVersion.cs

@@ -4,7 +4,7 @@ public class NullRequestedApiVersion : IRequestedApiVersion
 {
     public static NullRequestedApiVersion Instance = new NullRequestedApiVersion();
 
-    public string Current => null;
+    public string? Current => null;
 
     private NullRequestedApiVersion()
     {

framework/src/Volo.Abp.AspNetCore.Mvc/Volo/Abp/AspNetCore/Mvc/AbpAspNetCoreMvcModule.cs

@@ -233,7 +233,7 @@ public class AbpAspNetCoreMvcModule : AbpModule
             .GetRequiredService<IModuleContainer>()
             .Modules
             .Where(m => m.IsLoadedAsPlugIn)
-            .Select(m => m.Type.Assembly)
+            .SelectMany(m => m.AllAssemblies)
             .Distinct();
 
         AddToApplicationParts(partManager, moduleAssemblies);

framework/src/Volo.Abp.AspNetCore.Mvc/Volo/Abp/AspNetCore/Mvc/ApplicationPartSorter.cs

@@ -125,7 +125,7 @@ public static class ApplicationPartSorter
 
         var moduleDependedAssemblies = moduleDescriptor
             .Dependencies
-            .Select(d => d.Assembly)
+            .SelectMany(d => d.AllAssemblies)
             .ToArray();
 
         return partManager.ApplicationParts
@@ -161,6 +161,6 @@ public static class ApplicationPartSorter
     {
         return moduleContainer
             .Modules
-            .FirstOrDefault(m => m.Assembly == assembly);
+            .FirstOrDefault(m => m.AllAssemblies.Contains(assembly));
     }
 }

framework/src/Volo.Abp.AspNetCore.TestBase/Volo/Abp/AspNetCore/TestBase/AbpAspNetCoreIntegratedTestBase.cs

@@ -7,11 +7,15 @@ using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using Volo.Abp.Modularity;
 
 namespace Volo.Abp.AspNetCore.TestBase;
 
-public abstract class AbpAspNetCoreIntegratedTestBase<TStartup> : AbpTestBaseWithServiceProvider, IDisposable
-    where TStartup : class
+/// <typeparam name="TStartupModule">
+/// Can be a module type or old-style ASP.NET Core Startup class.
+/// </typeparam>
+public abstract class AbpAspNetCoreIntegratedTestBase<TStartupModule> : AbpTestBaseWithServiceProvider, IDisposable
+    where TStartupModule : class
 {
     protected TestServer Server { get; }
 
@@ -39,7 +43,15 @@ public abstract class AbpAspNetCoreIntegratedTestBase<TStartup> : AbpTestBaseWit
         return Host.CreateDefaultBuilder()
             .ConfigureWebHostDefaults(webBuilder =>
             {
-                webBuilder.UseStartup<TStartup>();
+                if (typeof(TStartupModule).IsAssignableTo<IAbpModule>())
+                {
+                    webBuilder.UseStartup<TestStartup<TStartupModule>>();
+                }
+                else
+                {
+                    webBuilder.UseStartup<TStartupModule>();
+                }
+                
                 webBuilder.UseAbpTestServer();
             })
             .UseAutofac()

framework/src/Volo.Abp.AspNetCore.TestBase/Volo/Abp/AspNetCore/TestBase/TestStartup.cs

@@ -0,0 +1,18 @@
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+using Volo.Abp.Threading;
+
+namespace Volo.Abp.AspNetCore.TestBase;
+
+internal class TestStartup<TStartupModule>
+{
+    public void ConfigureServices(IServiceCollection services)
+    {
+        AsyncHelper.RunSync(() => services.AddApplicationAsync(typeof(TStartupModule)));
+    }
+
+    public void Configure(IApplicationBuilder app)
+    {
+        AsyncHelper.RunSync(app.InitializeApplicationAsync);
+    }
+}

framework/src/Volo.Abp.Autofac.WebAssembly/Microsoft/AspNetCore/Components/WebAssembly/Hosting/AbpWebAssemblyApplicationCreationOptionsAutofacExtensions.cs

@@ -11,7 +11,7 @@ public static class AbpWebAssemblyApplicationCreationOptionsAutofacExtensions
 {
     public static void UseAutofac(
         [NotNull] this AbpWebAssemblyApplicationCreationOptions options,
-        [CanBeNull] Action<ContainerBuilder> configure = null)
+        Action<ContainerBuilder>? configure = null)
     {
         options.HostBuilder.Services.AddAutofacServiceProviderFactory();
         options.HostBuilder.ConfigureContainer(

framework/src/Volo.Abp.Autofac.WebAssembly/Volo.Abp.Autofac.WebAssembly.csproj

@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFramework>net7.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <RootNamespace />
     </PropertyGroup>
 

framework/src/Volo.Abp.Autofac/Autofac/Builder/AbpRegistrationBuilderExtensions.cs

@@ -69,7 +69,7 @@ public static class AbpRegistrationBuilderExtensions
         where TActivatorData : ReflectionActivatorData
     {
         // Enable Property Injection only for types in an assembly containing an AbpModule and without a DisablePropertyInjection attribute on class or properties.
-        if (moduleContainer.Modules.Any(m => m.Assembly == implementationType.Assembly) &&
+        if (moduleContainer.Modules.Any(m => m.AllAssemblies.Contains(implementationType.Assembly)) &&
             implementationType.GetCustomAttributes(typeof(DisablePropertyInjectionAttribute), true).IsNullOrEmpty())
         {
             registrationBuilder = registrationBuilder.PropertiesAutowired(new AbpPropertySelector(false));

framework/src/Volo.Abp.Autofac/Autofac/Extensions/DependencyInjection/AutofacRegistration.cs

@@ -87,7 +87,7 @@ public static class AutofacRegistration
     public static void Populate(
         this ContainerBuilder builder,
         IServiceCollection services,
-        object lifetimeScopeTagForSingletons)
+        object? lifetimeScopeTagForSingletons)
     {
         if (services == null)
         {
@@ -134,7 +134,7 @@ public static class AutofacRegistration
     private static IRegistrationBuilder<object, TActivatorData, TRegistrationStyle> ConfigureLifecycle<TActivatorData, TRegistrationStyle>(
         this IRegistrationBuilder<object, TActivatorData, TRegistrationStyle> registrationBuilder,
         ServiceLifetime lifecycleKind,
-        object lifetimeScopeTagForSingleton)
+        object? lifetimeScopeTagForSingleton)
     {
         switch (lifecycleKind)
         {
@@ -179,7 +179,7 @@ public static class AutofacRegistration
     private static void Register(
         ContainerBuilder builder,
         IServiceCollection services,
-        object lifetimeScopeTagForSingletons)
+        object? lifetimeScopeTagForSingletons)
     {
         var moduleContainer = services.GetSingletonInstance<IModuleContainer>();
         var registrationActionList = services.GetRegistrationActionList();
@@ -223,7 +223,7 @@ public static class AutofacRegistration
             else
             {
                 builder
-                    .RegisterInstance(descriptor.ImplementationInstance)
+                    .RegisterInstance(descriptor.ImplementationInstance!)
                     .As(descriptor.ServiceType)
                     .ConfigureLifecycle(descriptor.Lifetime, null);
             }

framework/src/Volo.Abp.Autofac/Microsoft/Extensions/DependencyInjection/AbpAutofacServiceCollectionExtensions.cs

@@ -21,7 +21,7 @@ public static class AbpAutofacServiceCollectionExtensions
         return builder;
     }
 
-    public static IServiceProvider BuildAutofacServiceProvider([NotNull] this IServiceCollection services, Action<ContainerBuilder> builderAction = null)
+    public static IServiceProvider BuildAutofacServiceProvider([NotNull] this IServiceCollection services, Action<ContainerBuilder>? builderAction = null)
     {
         return services.BuildServiceProviderFromFactory(builderAction);
     }

framework/src/Volo.Abp.Autofac/Volo.Abp.Autofac.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Autofac</AssemblyName>
     <PackageId>Volo.Abp.Autofac</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Autofac/Volo/Abp/Autofac/AbpAutofacServiceProviderFactory.cs

@@ -11,7 +11,7 @@ namespace Volo.Abp.Autofac;
 public class AbpAutofacServiceProviderFactory : IServiceProviderFactory<ContainerBuilder>
 {
     private readonly ContainerBuilder _builder;
-    private IServiceCollection _services;
+    private IServiceCollection _services = default!;
 
     public AbpAutofacServiceProviderFactory(ContainerBuilder builder)
     {

framework/src/Volo.Abp.Castle.Core/Volo.Abp.Castle.Core.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Castle.Core</AssemblyName>
     <PackageId>Volo.Abp.Castle.Core</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Castle.Core/Volo/Abp/Castle/DynamicProxy/CastleAbpMethodInvocationAdapterBase.cs

@@ -20,7 +20,7 @@ public abstract class CastleAbpMethodInvocationAdapterBase : IAbpMethodInvocatio
 
     public MethodInfo Method => Invocation.MethodInvocationTarget ?? Invocation.Method;
 
-    public object ReturnValue { get; set; }
+    public object ReturnValue { get; set; } = default!;
 
     protected IInvocation Invocation { get; }
 
@@ -39,7 +39,7 @@ public abstract class CastleAbpMethodInvocationAdapterBase : IAbpMethodInvocatio
         var methodParameters = Method.GetParameters();
         for (int i = 0; i < methodParameters.Length; i++)
         {
-            dict[methodParameters[i].Name] = Invocation.Arguments[i];
+            dict[methodParameters[i].Name!] = Invocation.Arguments[i];
         }
 
         return dict;

framework/src/Volo.Abp.Castle.Core/Volo/Abp/Castle/DynamicProxy/CastleAbpMethodInvocationAdapterWithReturnValue.cs

@@ -21,6 +21,6 @@ public class CastleAbpMethodInvocationAdapterWithReturnValue<TResult> : CastleAb
 
     public override async Task ProceedAsync()
     {
-        ReturnValue = await Proceed(Invocation, ProceedInfo);
+        ReturnValue = (await Proceed(Invocation, ProceedInfo))!;
     }
 }

framework/src/Volo.Abp.Core/Volo/Abp/AbpApplicationBase.cs

@@ -188,11 +188,13 @@ public abstract class AbpApplicationBase : IAbpApplication
             {
                 if (!abpModule.SkipAutoServiceRegistration)
                 {
-                    var assembly = module.Type.Assembly;
-                    if (!assemblies.Contains(assembly))
+                    foreach (var assembly in module.AllAssemblies)
                     {
-                        Services.AddAssembly(assembly);
-                        assemblies.Add(assembly);
+                        if (!assemblies.Contains(assembly))
+                        {
+                            Services.AddAssembly(assembly);
+                            assemblies.Add(assembly);
+                        }
                     }
                 }
             }
@@ -279,11 +281,13 @@ public abstract class AbpApplicationBase : IAbpApplication
             {
                 if (!abpModule.SkipAutoServiceRegistration)
                 {
-                    var assembly = module.Type.Assembly;
-                    if (!assemblies.Contains(assembly))
+                    foreach (var assembly in module.AllAssemblies)
                     {
-                        Services.AddAssembly(assembly);
-                        assemblies.Add(assembly);
+                        if (!assemblies.Contains(assembly))
+                        {
+                            Services.AddAssembly(assembly);
+                            assemblies.Add(assembly);
+                        }
                     }
                 }
             }

framework/src/Volo.Abp.Core/Volo/Abp/AbpException.cs

@@ -13,13 +13,13 @@ public class AbpException : Exception
 
     }
 
-    public AbpException(string message)
+    public AbpException(string? message)
         : base(message)
     {
 
     }
 
-    public AbpException(string message, Exception innerException)
+    public AbpException(string? message, Exception? innerException)
         : base(message, innerException)
     {
 

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/AbpModuleDescriptor.cs

@@ -11,6 +11,8 @@ public class AbpModuleDescriptor : IAbpModuleDescriptor
     public Type Type { get; }
 
     public Assembly Assembly { get; }
+    
+    public List<Assembly> AllAssemblies { get; }
 
     public IAbpModule Instance { get; }
 
@@ -26,6 +28,7 @@ public class AbpModuleDescriptor : IAbpModuleDescriptor
     {
         Check.NotNull(type, nameof(type));
         Check.NotNull(instance, nameof(instance));
+        AbpModule.CheckAbpModuleType(type);
 
         if (!type.GetTypeInfo().IsAssignableFrom(instance.GetType()))
         {
@@ -34,6 +37,7 @@ public class AbpModuleDescriptor : IAbpModuleDescriptor
 
         Type = type;
         Assembly = type.Assembly;
+        AllAssemblies = AbpModuleHelper.GetAllAssemblies(type);
         Instance = instance;
         IsLoadedAsPlugIn = isLoadedAsPlugIn;
 

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/AbpModuleHelper.cs

@@ -36,6 +36,27 @@ internal static class AbpModuleHelper
 
         return dependencies;
     }
+    
+    public static List<Assembly> GetAllAssemblies(Type moduleType)
+    {
+        var assemblies = new List<Assembly>();
+
+        var additionalAssemblyDescriptors = moduleType
+            .GetCustomAttributes()
+            .OfType<IAdditionalModuleAssemblyProvider>();
+
+        foreach (var descriptor in additionalAssemblyDescriptors)
+        {
+            foreach (var assembly in descriptor.GetAssemblies())
+            {
+                assemblies.AddIfNotContains(assembly);
+            }
+        }
+        
+        assemblies.Add(moduleType.Assembly);
+
+        return assemblies;
+    }
 
     private static void AddModuleAndDependenciesRecursively(
         List<Type> moduleTypes,

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/AdditionalAssemblyAttribute.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Linq;
+using System.Reflection;
+
+namespace Volo.Abp.Modularity;
+
+/// <summary>
+/// Used to define additional assemblies for a module.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
+public class AdditionalAssemblyAttribute : Attribute, IAdditionalModuleAssemblyProvider
+{
+    public Type[] TypesInAssemblies { get; }
+
+    public AdditionalAssemblyAttribute(params Type[]? typesInAssemblies)
+    {
+        TypesInAssemblies = typesInAssemblies ?? Type.EmptyTypes;
+    }
+
+    public virtual Assembly[] GetAssemblies()
+    {
+        return TypesInAssemblies.Select(t => t.Assembly).Distinct().ToArray();
+    }
+}

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/DependsOnAttribute.cs

@@ -1,5 +1,4 @@
 using System;
-using JetBrains.Annotations;
 
 namespace Volo.Abp.Modularity;
 
@@ -9,12 +8,11 @@ namespace Volo.Abp.Modularity;
 [AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
 public class DependsOnAttribute : Attribute, IDependedTypesProvider
 {
-    [NotNull]
     public Type[] DependedTypes { get; }
 
     public DependsOnAttribute(params Type[]? dependedTypes)
     {
-        DependedTypes = dependedTypes ?? new Type[0];
+        DependedTypes = dependedTypes ?? Type.EmptyTypes;
     }
 
     public virtual Type[] GetDependedTypes()

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/IAbpModuleDescriptor.cs

@@ -6,13 +6,36 @@ namespace Volo.Abp.Modularity;
 
 public interface IAbpModuleDescriptor
 {
+    /// <summary>
+    /// Type of the module class.
+    /// </summary>
     Type Type { get; }
 
+    /// <summary>
+    /// Main assembly that defines the module <see cref="Type"/>.
+    /// </summary>
     Assembly Assembly { get; }
+    
+    /// <summary>
+    /// All the assemblies of the module.
+    /// Includes the main <see cref="Assembly"/> and other assemblies defined
+    /// on the module <see cref="Type"/> using the <see cref="AdditionalAssemblyAttribute"/> attribute.
+    /// </summary>
+    List<Assembly> AllAssemblies { get; }
 
+    /// <summary>
+    /// The instance of the module class (singleton).
+    /// </summary>
     IAbpModule Instance { get; }
 
+    /// <summary>
+    /// Is this module loaded as a plug-in?
+    /// </summary>
     bool IsLoadedAsPlugIn { get; }
 
+    /// <summary>
+    /// Modules on which this module depends on.
+    /// A module can depend on another module using the <see cref="DependsOnAttribute"/> attribute.
+    /// </summary>
     IReadOnlyList<IAbpModuleDescriptor> Dependencies { get; }
 }

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/IAdditionalModuleAssemblyProvider.cs

@@ -0,0 +1,8 @@
+using System.Reflection;
+
+namespace Volo.Abp.Modularity;
+
+public interface IAdditionalModuleAssemblyProvider
+{
+    Assembly[] GetAssemblies();
+}

framework/src/Volo.Abp.Core/Volo/Abp/Reflection/AssemblyFinder.cs

@@ -29,7 +29,7 @@ public class AssemblyFinder : IAssemblyFinder
 
         foreach (var module in _moduleContainer.Modules)
         {
-            assemblies.Add(module.Type.Assembly);
+            assemblies.AddRange(module.AllAssemblies);
         }
 
         return assemblies.Distinct().ToImmutableList();

framework/src/Volo.Abp.Data/Volo.Abp.Data.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Data</AssemblyName>
     <PackageId>Volo.Abp.Data</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Data/Volo/Abp/Data/AbpCommonDbProperties.cs

@@ -13,5 +13,5 @@ public static class AbpCommonDbProperties
     /// <summary>
     /// Default value: null.
     /// </summary>
-    public static string DbSchema { get; set; } = null;
+    public static string? DbSchema { get; set; } = null;
 }

framework/src/Volo.Abp.Data/Volo/Abp/Data/AbpDataMigrationEnvironmentExtensions.cs

@@ -6,17 +6,17 @@ namespace Volo.Abp.Data;
 
 public static class AbpDataMigrationEnvironmentExtensions
 {
-    public static void AddDataMigrationEnvironment(this AbpApplicationCreationOptions options, AbpDataMigrationEnvironment environment = null)
+    public static void AddDataMigrationEnvironment(this AbpApplicationCreationOptions options, AbpDataMigrationEnvironment? environment = null)
     {
         options.Services.AddDataMigrationEnvironment(environment ?? new AbpDataMigrationEnvironment());
     }
 
-    public static void AddDataMigrationEnvironment(this IServiceCollection services, AbpDataMigrationEnvironment environment = null)
+    public static void AddDataMigrationEnvironment(this IServiceCollection services, AbpDataMigrationEnvironment? environment = null)
     {
         services.AddObjectAccessor<AbpDataMigrationEnvironment>(environment ?? new AbpDataMigrationEnvironment());
     }
 
-    public static AbpDataMigrationEnvironment GetDataMigrationEnvironment(this IServiceCollection services)
+    public static AbpDataMigrationEnvironment? GetDataMigrationEnvironment(this IServiceCollection services)
     {
         return services.GetObjectOrNull<AbpDataMigrationEnvironment>();
     }
@@ -26,7 +26,7 @@ public static class AbpDataMigrationEnvironmentExtensions
         return services.GetDataMigrationEnvironment() != null;
     }
 
-    public static AbpDataMigrationEnvironment GetDataMigrationEnvironment(this IServiceProvider serviceProvider)
+    public static AbpDataMigrationEnvironment? GetDataMigrationEnvironment(this IServiceProvider serviceProvider)
     {
         return serviceProvider.GetService<IObjectAccessor<AbpDataMigrationEnvironment>>()?.Value;
     }

framework/src/Volo.Abp.Data/Volo/Abp/Data/AbpDatabaseInfoDictionary.cs

@@ -13,8 +13,7 @@ public class AbpDatabaseInfoDictionary : Dictionary<string, AbpDatabaseInfo>
         ConnectionIndex = new Dictionary<string, AbpDatabaseInfo>();
     }
 
-    [CanBeNull]
-    public AbpDatabaseInfo GetMappedDatabaseOrNull(string connectionStringName)
+    public AbpDatabaseInfo? GetMappedDatabaseOrNull(string connectionStringName)
     {
         return ConnectionIndex.GetOrDefault(connectionStringName);
     }

framework/src/Volo.Abp.Data/Volo/Abp/Data/AbpDbConnectionOptions.cs

@@ -15,7 +15,7 @@ public class AbpDbConnectionOptions
         Databases = new AbpDatabaseInfoDictionary();
     }
 
-    public string GetConnectionStringOrNull(
+    public string? GetConnectionStringOrNull(
         string connectionStringName,
         bool fallbackToDatabaseMappings = true,
         bool fallbackToDefault = true)

framework/src/Volo.Abp.Data/Volo/Abp/Data/AppliedDatabaseMigrationsEto.cs

@@ -7,6 +7,6 @@ namespace Volo.Abp.Data;
 [EventName("abp.data.applied_database_migrations")]
 public class AppliedDatabaseMigrationsEto
 {
-    public string DatabaseName { get; set; }
+    public string DatabaseName { get; set; } = default!;
     public Guid? TenantId { get; set; }
 }

framework/src/Volo.Abp.Data/Volo/Abp/Data/ApplyDatabaseMigrationsEto.cs

@@ -10,5 +10,5 @@ public class ApplyDatabaseMigrationsEto : EtoBase
 {
     public Guid? TenantId { get; set; }
 
-    public string DatabaseName { get; set; }
+    public string DatabaseName { get; set; } = default!;
 }

framework/src/Volo.Abp.Data/Volo/Abp/Data/ConcurrencyStampExtensions.cs

@@ -7,11 +7,11 @@ namespace Volo.Abp.Data;
 
 public static class ConcurrencyStampExtensions
 {
-    public static void SetConcurrencyStampIfNotNull(this IHasConcurrencyStamp entity, [CanBeNull] string concurrencyStamp)
+    public static void SetConcurrencyStampIfNotNull(this IHasConcurrencyStamp entity, string? concurrencyStamp)
     {
         if (!concurrencyStamp.IsNullOrEmpty())
         {
-            entity.ConcurrencyStamp = concurrencyStamp;
+            entity.ConcurrencyStamp = concurrencyStamp!;
         }
     }
 }

framework/src/Volo.Abp.Data/Volo/Abp/Data/ConnectionStringNameAttribute.cs

@@ -27,7 +27,7 @@ public class ConnectionStringNameAttribute : Attribute
 
         if (nameAttribute == null)
         {
-            return type.FullName;
+            return type.FullName!;
         }
 
         return nameAttribute.Name;

framework/src/Volo.Abp.Data/Volo/Abp/Data/ConnectionStrings.cs

@@ -4,11 +4,11 @@ using System.Collections.Generic;
 namespace Volo.Abp.Data;
 
 [Serializable]
-public class ConnectionStrings : Dictionary<string, string>
+public class ConnectionStrings : Dictionary<string, string?>
 {
     public const string DefaultConnectionStringName = "Default";
 
-    public string Default {
+    public string? Default {
         get => this.GetOrDefault(DefaultConnectionStringName);
         set => this[DefaultConnectionStringName] = value;
     }

framework/src/Volo.Abp.Data/Volo/Abp/Data/DataFilter.cs

@@ -42,10 +42,10 @@ public class DataFilter : IDataFilter, ISingletonDependency
     private IDataFilter<TFilter> GetFilter<TFilter>()
         where TFilter : class
     {
-        return _filters.GetOrAdd(
+        return (_filters.GetOrAdd(
             typeof(TFilter),
-             factory: () => _serviceProvider.GetRequiredService<IDataFilter<TFilter>>()
-        ) as IDataFilter<TFilter>;
+            factory: () => _serviceProvider.GetRequiredService<IDataFilter<TFilter>>()
+        ) as IDataFilter<TFilter>)!;
     }
 }
 
@@ -55,7 +55,7 @@ public class DataFilter<TFilter> : IDataFilter<TFilter>
     public bool IsEnabled {
         get {
             EnsureInitialized();
-            return _filter.Value.IsEnabled;
+            return _filter.Value!.IsEnabled;
         }
     }
 
@@ -76,7 +76,7 @@ public class DataFilter<TFilter> : IDataFilter<TFilter>
             return NullDisposable.Instance;
         }
 
-        _filter.Value.IsEnabled = true;
+        _filter.Value!.IsEnabled = true;
 
         return new DisposeAction(() => Disable());
     }
@@ -88,7 +88,7 @@ public class DataFilter<TFilter> : IDataFilter<TFilter>
             return NullDisposable.Instance;
         }
 
-        _filter.Value.IsEnabled = false;
+        _filter.Value!.IsEnabled = false;
 
         return new DisposeAction(() => Enable());
     }

framework/src/Volo.Abp.Data/Volo/Abp/Data/DataSeedContext.cs

@@ -16,8 +16,7 @@ public class DataSeedContext
     /// Returns the value in the <see cref="Properties"/> dictionary by given <paramref name="name"/>.
     /// Returns null if given <paramref name="name"/> is not present in the <see cref="Properties"/> dictionary.
     /// </returns>
-    [CanBeNull]
-    public object this[string name] {
+    public object? this[string name] {
         get => Properties.GetOrDefault(name);
         set => Properties[name] = value;
     }
@@ -26,19 +25,19 @@ public class DataSeedContext
     /// Can be used to get/set custom properties.
     /// </summary>
     [NotNull]
-    public Dictionary<string, object> Properties { get; }
+    public Dictionary<string, object?> Properties { get; }
 
     public DataSeedContext(Guid? tenantId = null)
     {
         TenantId = tenantId;
-        Properties = new Dictionary<string, object>();
+        Properties = new Dictionary<string, object?>();
     }
 
     /// <summary>
     /// Sets a property in the <see cref="Properties"/> dictionary.
     /// This is a shortcut for nested calls on this object.
     /// </summary>
-    public virtual DataSeedContext WithProperty(string key, object value)
+    public virtual DataSeedContext WithProperty(string key, object? value)
     {
         Properties[key] = value;
         return this;

framework/src/Volo.Abp.Data/Volo/Abp/Data/DataSeeder.cs

@@ -33,9 +33,9 @@ public class DataSeeder : IDataSeeder, ITransientDependency
                 foreach (var contributorType in Options.Contributors)
                 {
                     var options = context.Properties.TryGetValue(DataSeederExtensions.SeedInSeparateUowOptions, out var uowOptions)
-                        ? (AbpUnitOfWorkOptions) uowOptions
+                        ? (AbpUnitOfWorkOptions) uowOptions!
                         : new AbpUnitOfWorkOptions();
-                    var requiresNew = context.Properties.TryGetValue(DataSeederExtensions.SeedInSeparateUowRequiresNew, out var obj) && (bool) obj;
+                    var requiresNew = context.Properties.TryGetValue(DataSeederExtensions.SeedInSeparateUowRequiresNew, out var obj) && (bool) obj!;
 
                     using (var uow = manager.Begin(options, requiresNew))
                     {

framework/src/Volo.Abp.Data/Volo/Abp/Data/DataSeederExtensions.cs

@@ -15,7 +15,7 @@ public static class DataSeederExtensions
         return seeder.SeedAsync(new DataSeedContext(tenantId));
     }
 
-    public static Task SeedInSeparateUowAsync(this IDataSeeder seeder, Guid? tenantId = null, AbpUnitOfWorkOptions options = null, bool requiresNew = false)
+    public static Task SeedInSeparateUowAsync(this IDataSeeder seeder, Guid? tenantId = null, AbpUnitOfWorkOptions? options = null, bool requiresNew = false)
     {
         var context = new DataSeedContext(tenantId);
         context.WithProperty(SeedInSeparateUow, true);

framework/src/Volo.Abp.Data/Volo/Abp/Data/DefaultConnectionStringResolver.cs

@@ -16,17 +16,17 @@ public class DefaultConnectionStringResolver : IConnectionStringResolver, ITrans
     }
 
     [Obsolete("Use ResolveAsync method.")]
-    public virtual string Resolve(string connectionStringName = null)
+    public virtual string Resolve(string? connectionStringName = null)
     {
-        return ResolveInternal(connectionStringName);
+        return ResolveInternal(connectionStringName)!;
     }
 
-    public virtual Task<string> ResolveAsync(string connectionStringName = null)
+    public virtual Task<string> ResolveAsync(string? connectionStringName = null)
     {
-        return Task.FromResult(ResolveInternal(connectionStringName));
+        return Task.FromResult(ResolveInternal(connectionStringName))!;
     }
 
-    private string ResolveInternal(string connectionStringName)
+    private string? ResolveInternal(string? connectionStringName)
     {
         if (connectionStringName == null)
         {

framework/src/Volo.Abp.Data/Volo/Abp/Data/IConnectionStringResolver.cs

@@ -8,8 +8,8 @@ public interface IConnectionStringResolver
 {
     [NotNull]
     [Obsolete("Use ResolveAsync method.")]
-    string Resolve(string connectionStringName = null);
+    string Resolve(string? connectionStringName = null);
 
     [NotNull]
-    Task<string> ResolveAsync(string connectionStringName = null);
+    Task<string> ResolveAsync(string? connectionStringName = null);
 }

framework/src/Volo.Abp.ExceptionHandling/Volo.Abp.ExceptionHandling.csproj

@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
         <RootNamespace />
     </PropertyGroup>

framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/DefaultExceptionToErrorInfoConverter.cs

@@ -54,7 +54,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         return errorInfo;
     }
 
-    public RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions> options = null)
+    public RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions>? options = null)
     {
         var exceptionHandlingOptions = CreateDefaultOptions();
         options?.Invoke(exceptionHandlingOptions);
@@ -90,7 +90,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
         if (exception is EntityNotFoundException)
         {
-            return CreateEntityNotFoundError(exception as EntityNotFoundException);
+            return CreateEntityNotFoundError((exception as EntityNotFoundException)!);
         }
 
         var errorInfo = new RemoteServiceErrorInfo();
@@ -110,10 +110,10 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
             if (errorInfo.Details.IsNullOrEmpty())
             {
-                errorInfo.Details = GetValidationErrorNarrative(exception as IHasValidationErrors);
+                errorInfo.Details = GetValidationErrorNarrative((exception as IHasValidationErrors)!);
             }
 
-            errorInfo.ValidationErrors = GetValidationErrorInfos(exception as IHasValidationErrors);
+            errorInfo.ValidationErrors = GetValidationErrorInfos((exception as IHasValidationErrors)!);
         }
 
         TryToLocalizeExceptionMessage(exception, errorInfo);
@@ -146,7 +146,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         }
 
         if (exceptionWithErrorCode.Code.IsNullOrWhiteSpace() ||
-            !exceptionWithErrorCode.Code.Contains(":"))
+            !exceptionWithErrorCode.Code!.Contains(":"))
         {
             return;
         }
@@ -197,10 +197,8 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
     protected virtual Exception TryToGetActualException(Exception exception)
     {
-        if (exception is AggregateException && exception.InnerException != null)
+        if (exception is AggregateException aggException && aggException.InnerException != null)
         {
-            var aggException = exception as AggregateException;
-
             if (aggException.InnerException is AbpValidationException ||
                 aggException.InnerException is AbpAuthorizationException ||
                 aggException.InnerException is EntityNotFoundException ||
@@ -223,7 +221,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
         if (exception is AbpValidationException)
         {
-            errorInfo.ValidationErrors = GetValidationErrorInfos(exception as AbpValidationException);
+            errorInfo.ValidationErrors = GetValidationErrorInfos((exception as AbpValidationException)!);
         }
 
         return errorInfo;
@@ -246,9 +244,8 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         }
 
         //Additional info for AbpValidationException
-        if (exception is AbpValidationException)
+        if (exception is AbpValidationException validationException)
         {
-            var validationException = exception as AbpValidationException;
             if (validationException.ValidationErrors.Count > 0)
             {
                 detailBuilder.AppendLine(GetValidationErrorNarrative(validationException));
@@ -268,9 +265,8 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         }
 
         //Inner exceptions for AggregateException
-        if (exception is AggregateException)
+        if (exception is AggregateException aggException)
         {
-            var aggException = exception as AggregateException;
             if (aggException.InnerExceptions.IsNullOrEmpty())
             {
                 return;
@@ -289,7 +285,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
         foreach (var validationResult in validationException.ValidationErrors)
         {
-            var validationError = new RemoteServiceValidationErrorInfo(validationResult.ErrorMessage);
+            var validationError = new RemoteServiceValidationErrorInfo(validationResult.ErrorMessage!);
 
             if (validationResult.MemberNames != null && validationResult.MemberNames.Any())
             {

framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/IExceptionToErrorInfoConverter.cs

@@ -24,5 +24,5 @@ public interface IExceptionToErrorInfoConverter
     /// <param name="exception">The exception.</param>
     /// <param name="options">Additional options.</param>
     /// <returns>Error info or null</returns>
-    RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions> options = null);
+    RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions>? options = null);
 }

framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Domain/Entities/EntityNotFoundException.cs

@@ -10,12 +10,12 @@ public class EntityNotFoundException : AbpException
     /// <summary>
     /// Type of the entity.
     /// </summary>
-    public Type EntityType { get; set; }
+    public Type? EntityType { get; set; }
 
     /// <summary>
     /// Id of the Entity.
     /// </summary>
-    public object Id { get; set; }
+    public object? Id { get; set; }
 
     /// <summary>
     /// Creates a new <see cref="EntityNotFoundException"/> object.
@@ -37,7 +37,7 @@ public class EntityNotFoundException : AbpException
     /// <summary>
     /// Creates a new <see cref="EntityNotFoundException"/> object.
     /// </summary>
-    public EntityNotFoundException(Type entityType, object id)
+    public EntityNotFoundException(Type entityType, object? id)
         : this(entityType, id, null)
     {
 
@@ -46,7 +46,7 @@ public class EntityNotFoundException : AbpException
     /// <summary>
     /// Creates a new <see cref="EntityNotFoundException"/> object.
     /// </summary>
-    public EntityNotFoundException(Type entityType, object id, Exception innerException)
+    public EntityNotFoundException(Type entityType, object? id, Exception? innerException)
         : base(
             id == null
                 ? $"There is no such an entity given id. Entity type: {entityType.FullName}"

framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/Client/AbpRemoteCallException.cs

@@ -9,18 +9,18 @@ public class AbpRemoteCallException : AbpException, IHasErrorCode, IHasErrorDeta
 {
     public int HttpStatusCode { get; set; }
 
-    public string Code => Error?.Code;
+    public string? Code => Error?.Code;
 
-    public string Details => Error?.Details;
+    public string? Details => Error?.Details;
 
-    public RemoteServiceErrorInfo Error { get; set; }
+    public RemoteServiceErrorInfo? Error { get; set; }
 
     public AbpRemoteCallException()
     {
 
     }
 
-    public AbpRemoteCallException(string message, Exception innerException = null)
+    public AbpRemoteCallException(string message, Exception? innerException = null)
         : base(message, innerException)
     {
 
@@ -32,7 +32,7 @@ public class AbpRemoteCallException : AbpException, IHasErrorCode, IHasErrorDeta
 
     }
 
-    public AbpRemoteCallException(RemoteServiceErrorInfo error, Exception innerException = null)
+    public AbpRemoteCallException(RemoteServiceErrorInfo error, Exception? innerException = null)
         : base(error.Message, innerException)
     {
         Error = error;

framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceErrorInfo.cs

@@ -12,27 +12,27 @@ public class RemoteServiceErrorInfo
     /// <summary>
     /// Error code.
     /// </summary>
-    public string Code { get; set; }
+    public string? Code { get; set; }
 
     /// <summary>
     /// Error message.
     /// </summary>
-    public string Message { get; set; }
+    public string? Message { get; set; }
 
     /// <summary>
     /// Error details.
     /// </summary>
-    public string Details { get; set; }
+    public string? Details { get; set; }
 
     /// <summary>
     /// Error data.
     /// </summary>
-    public IDictionary Data { get; set; }
+    public IDictionary? Data { get; set; }
 
     /// <summary>
     /// Validation errors if exists.
     /// </summary>
-    public RemoteServiceValidationErrorInfo[] ValidationErrors { get; set; }
+    public RemoteServiceValidationErrorInfo[]? ValidationErrors { get; set; }
 
     /// <summary>
     /// Creates a new instance of <see cref="RemoteServiceErrorInfo"/>.
@@ -49,7 +49,7 @@ public class RemoteServiceErrorInfo
     /// <param name="details">Error details</param>
     /// <param name="message">Error message</param>
     /// <param name="data">Error data</param>
-    public RemoteServiceErrorInfo(string message, string details = null, string code = null, IDictionary data = null)
+    public RemoteServiceErrorInfo(string message, string? details = null, string? code = null, IDictionary? data = null)
     {
         Message = message;
         Details = details;

framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceValidationErrorInfo.cs

@@ -11,12 +11,12 @@ public class RemoteServiceValidationErrorInfo
     /// <summary>
     /// Validation error message.
     /// </summary>
-    public string Message { get; set; }
+    public string Message { get; set; } = default!;
 
     /// <summary>
     /// Relate invalid members (fields/properties).
     /// </summary>
-    public string[] Members { get; set; }
+    public string[] Members { get; set; } = default!;
 
     /// <summary>
     /// Creates a new instance of <see cref="RemoteServiceValidationErrorInfo"/>.

framework/src/Volo.Abp.Guids/Volo.Abp.Guids.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Guids</AssemblyName>
     <PackageId>Volo.Abp.Guids</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Http.Client.Web/Volo/Abp/Http/Client/Web/AbpHttpClientWebModule.cs

@@ -31,7 +31,7 @@ public class AbpHttpClientWebModule : AbpModule
             .ServiceProvider
             .GetRequiredService<IModuleContainer>()
             .Modules
-            .Select(m => m.Type.Assembly)
+            .SelectMany(m => m.AllAssemblies)
             .Where(a => a.GetTypes().Any(AbpHttpClientProxyHelper.IsClientProxyService))
             .Distinct())
         {

framework/src/Volo.Abp.Json.Abstractions/Volo.Abp.Json.Abstractions.csproj

@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <PackageId>Volo.Abp.Json.Abstractions</PackageId>
         <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
         <GenerateAssemblyConfigurationAttribute>false</GenerateAssemblyConfigurationAttribute>

framework/src/Volo.Abp.Json.Abstractions/Volo/Abp/Json/AbpJsonOptions.cs

@@ -12,7 +12,7 @@ public class AbpJsonOptions
     /// <summary>
     /// Format of output json date, Null or empty string means default format.
     /// </summary>
-    public string OutputDateTimeFormat { get; set; }
+    public string? OutputDateTimeFormat { get; set; }
 
     public AbpJsonOptions()
     {

framework/src/Volo.Abp.Json.Newtonsoft/Volo.Abp.Json.Newtonsoft.csproj

@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <AssemblyName>Volo.Abp.Json.Newtonsoft</AssemblyName>
         <PackageId>Volo.Abp.Json.Newtonsoft</PackageId>
         <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Json.Newtonsoft/Volo/Abp/Json/Newtonsoft/AbpDateTimeConverter.cs

@@ -31,7 +31,7 @@ public class AbpDateTimeConverter : DateTimeConverterBase, ITransientDependency
         return objectType == typeof(DateTime) || objectType == typeof(DateTime?);
     }
 
-    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+    public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
     {
         var nullable = Nullable.GetUnderlyingType(objectType) != null;
         if (reader.TokenType == JsonToken.Null)
@@ -46,7 +46,7 @@ public class AbpDateTimeConverter : DateTimeConverterBase, ITransientDependency
 
         if (reader.TokenType == JsonToken.Date)
         {
-            return _clock.Normalize(reader.Value.To<DateTime>());
+            return _clock.Normalize(reader.Value!.To<DateTime>());
         }
 
         if (reader.TokenType != JsonToken.String)
@@ -72,11 +72,11 @@ public class AbpDateTimeConverter : DateTimeConverterBase, ITransientDependency
             }
         }
 
-        var date = DateTime.Parse(dateText, _culture, _dateTimeStyles);
+        var date = DateTime.Parse(dateText!, _culture, _dateTimeStyles);
         return _clock.Normalize(date);
     }
 
-    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
+    public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer)
     {
         if (value != null)
         {
@@ -97,7 +97,7 @@ public class AbpDateTimeConverter : DateTimeConverterBase, ITransientDependency
         }
         else
         {
-            throw new JsonSerializationException($"Unexpected value when converting date. Expected DateTime or DateTimeOffset, got {value.GetType()}.");
+            throw new JsonSerializationException($"Unexpected value when converting date. Expected DateTime or DateTimeOffset, got {value?.GetType()}.");
         }
     }
 

framework/src/Volo.Abp.Json.Newtonsoft/Volo/Abp/Json/Newtonsoft/AbpNewtonsoftJsonSerializer.cs

@@ -26,12 +26,12 @@ public class AbpNewtonsoftJsonSerializer : IJsonSerializer, ITransientDependency
 
     public T Deserialize<T>(string jsonString, bool camelCase = true)
     {
-        return JsonConvert.DeserializeObject<T>(jsonString, CreateJsonSerializerOptions(camelCase));
+        return JsonConvert.DeserializeObject<T>(jsonString, CreateJsonSerializerOptions(camelCase))!;
     }
 
     public object Deserialize(Type type, string jsonString, bool camelCase = true)
     {
-        return JsonConvert.DeserializeObject(jsonString, type, CreateJsonSerializerOptions(camelCase));
+        return JsonConvert.DeserializeObject(jsonString, type, CreateJsonSerializerOptions(camelCase))!;
     }
 
     private readonly static ConcurrentDictionary<object, JsonSerializerSettings> JsonSerializerOptionsCache =

framework/src/Volo.Abp.Json.SystemTextJson/Volo.Abp.Json.SystemTextJson.csproj

@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <AssemblyName>Volo.Abp.Json.SystemTextJson</AssemblyName>
         <PackageId>Volo.Abp.Json.SystemTextJson</PackageId>
         <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonSerializer.cs

@@ -22,12 +22,12 @@ public class AbpSystemTextJsonSerializer : IJsonSerializer, ITransientDependency
 
     public T Deserialize<T>(string jsonString, bool camelCase = true)
     {
-        return JsonSerializer.Deserialize<T>(jsonString, CreateJsonSerializerOptions(camelCase));
+        return JsonSerializer.Deserialize<T>(jsonString, CreateJsonSerializerOptions(camelCase))!;
     }
 
     public object Deserialize(Type type, string jsonString, bool camelCase = true)
     {
-        return JsonSerializer.Deserialize(jsonString, type, CreateJsonSerializerOptions(camelCase));
+        return JsonSerializer.Deserialize(jsonString, type, CreateJsonSerializerOptions(camelCase))!;
     }
 
     private static readonly ConcurrentDictionary<object, JsonSerializerOptions> JsonSerializerOptionsCache =

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpNullableStringToGuidConverter.cs

@@ -6,7 +6,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpNullableStringToGuidConverter : JsonConverter<Guid?>
 {
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public override Guid? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToBooleanConverter.cs

@@ -8,7 +8,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpStringToBooleanConverter : JsonConverter<bool>
 {
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public override bool Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumConverter.cs

@@ -9,9 +9,9 @@ public class AbpStringToEnumConverter<T> : JsonConverter<T>
 {
     private readonly JsonStringEnumConverter _innerJsonStringEnumConverter;
 
-    private JsonSerializerOptions _readJsonSerializerOptions;
+    private JsonSerializerOptions? _readJsonSerializerOptions;
 
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public AbpStringToEnumConverter()
         : this(namingPolicy: null, allowIntegerValues: true)
@@ -19,7 +19,7 @@ public class AbpStringToEnumConverter<T> : JsonConverter<T>
 
     }
 
-    public AbpStringToEnumConverter(JsonNamingPolicy namingPolicy = null, bool allowIntegerValues = true)
+    public AbpStringToEnumConverter(JsonNamingPolicy? namingPolicy = null, bool allowIntegerValues = true)
     {
         _innerJsonStringEnumConverter = new JsonStringEnumConverter(namingPolicy, allowIntegerValues);
     }
@@ -50,11 +50,11 @@ public class AbpStringToEnumConverter<T> : JsonConverter<T>
 
     public override T ReadAsPropertyName(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {
-        return (T)Enum.Parse(typeToConvert, reader.GetString());
+        return (T)Enum.Parse(typeToConvert, reader.GetString()!);
     }
 
     public override void WriteAsPropertyName(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
     {
-        writer.WritePropertyName(Enum.GetName(typeof(T), value));
+        writer.WritePropertyName(Enum.GetName(typeof(T), value)!);
     }
 }

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumFactory.cs

@@ -7,7 +7,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpStringToEnumFactory : JsonConverterFactory
 {
-    private readonly JsonNamingPolicy _namingPolicy;
+    private readonly JsonNamingPolicy? _namingPolicy;
     private readonly bool _allowIntegerValues;
 
     public AbpStringToEnumFactory()
@@ -16,7 +16,7 @@ public class AbpStringToEnumFactory : JsonConverterFactory
 
     }
 
-    public AbpStringToEnumFactory(JsonNamingPolicy namingPolicy, bool allowIntegerValues)
+    public AbpStringToEnumFactory(JsonNamingPolicy? namingPolicy, bool allowIntegerValues)
     {
         _namingPolicy = namingPolicy;
         _allowIntegerValues = allowIntegerValues;
@@ -33,7 +33,7 @@ public class AbpStringToEnumFactory : JsonConverterFactory
             typeof(AbpStringToEnumConverter<>).MakeGenericType(typeToConvert),
             BindingFlags.Instance | BindingFlags.Public,
             binder: null,
-            new object[] { _namingPolicy, _allowIntegerValues },
+            new object?[] { _namingPolicy, _allowIntegerValues },
             culture: null)!;
     }
 }

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToGuidConverter.cs

@@ -6,7 +6,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpStringToGuidConverter : JsonConverter<Guid>
 {
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public override Guid Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/ObjectToInferredTypesConverter.cs

@@ -12,16 +12,16 @@ public class ObjectToInferredTypesConverter : JsonConverter<object>
     public override object Read(
         ref Utf8JsonReader reader,
         Type typeToConvert,
-        JsonSerializerOptions options) => reader.TokenType switch
-        {
-            JsonTokenType.True => true,
-            JsonTokenType.False => false,
-            JsonTokenType.Number when reader.TryGetInt64(out long l) => l,
-            JsonTokenType.Number => reader.GetDouble(),
-            JsonTokenType.String when reader.TryGetDateTime(out DateTime datetime) => datetime,
-            JsonTokenType.String => reader.GetString(),
-            _ => JsonDocument.ParseValue(ref reader).RootElement.Clone()
-        };
+        JsonSerializerOptions options) => (reader.TokenType switch
+    {
+        JsonTokenType.True => true,
+        JsonTokenType.False => false,
+        JsonTokenType.Number when reader.TryGetInt64(out long l) => l,
+        JsonTokenType.Number => reader.GetDouble(),
+        JsonTokenType.String when reader.TryGetDateTime(out DateTime datetime) => datetime,
+        JsonTokenType.String => reader.GetString(),
+        _ => JsonDocument.ParseValue(ref reader).RootElement.Clone()
+    })!;
 
     public override void Write(
         Utf8JsonWriter writer,

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpDateTimeConverterModifier.cs

@@ -10,7 +10,7 @@ namespace Volo.Abp.Json.SystemTextJson.Modifiers;
 
 public class AbpDateTimeConverterModifier
 {
-    private IServiceProvider _serviceProvider;
+    private IServiceProvider _serviceProvider = default!;
 
     public Action<JsonTypeInfo> CreateModifyAction(IServiceProvider serviceProvider)
     {

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIgnorePropertiesModifiers.cs

@@ -9,7 +9,7 @@ namespace Volo.Abp.Json.SystemTextJson.Modifiers;
 public class AbpIgnorePropertiesModifiers<TClass, TProperty>
     where TClass : class
 {
-    private Expression<Func<TClass, TProperty>> _propertySelector;
+    private Expression<Func<TClass, TProperty>> _propertySelector = default!;
 
     public Action<JsonTypeInfo> CreateModifyAction(Expression<Func<TClass, TProperty>> propertySelector)
     {

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeExtraPropertiesModifiers.cs

@@ -17,7 +17,7 @@ public static class AbpIncludeExtraPropertiesModifiers
                 .Where(x => x.AttributeProvider is MemberInfo)
                 .FirstOrDefault(x =>
                     x.PropertyType == typeof(ExtraPropertyDictionary) &&
-                    x.AttributeProvider.As<MemberInfo>().Name == nameof(ExtensibleObject.ExtraProperties) &&
+                    x.AttributeProvider!.As<MemberInfo>().Name == nameof(ExtensibleObject.ExtraProperties) &&
                     x.Set == null);
 
             if (propertyJsonInfo != null)

framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeNonPublicPropertiesModifiers.cs

@@ -9,7 +9,7 @@ namespace Volo.Abp.Json.SystemTextJson.Modifiers;
 public class AbpIncludeNonPublicPropertiesModifiers<TClass, TProperty>
     where TClass : class
 {
-    private Expression<Func<TClass, TProperty>> _propertySelector;
+    private Expression<Func<TClass, TProperty>> _propertySelector = default!;
 
     public Action<JsonTypeInfo> CreateModifyAction(Expression<Func<TClass, TProperty>> propertySelector)
     {

framework/src/Volo.Abp.Ldap.Abstractions/Volo.Abp.Ldap.Abstractions.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Ldap.Abstractions</AssemblyName>
     <PackageId>Volo.Abp.Ldap.Abstractions</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Ldap.Abstractions/Volo/Abp/Ldap/ILdapSettingProvider.cs

@@ -4,15 +4,15 @@ namespace Volo.Abp.Ldap;
 
 public interface ILdapSettingProvider
 {
-    public Task<string> GetServerHostAsync();
+    public Task<string?> GetServerHostAsync();
 
     public Task<int> GetServerPortAsync();
 
-    public Task<string> GetBaseDcAsync();
+    public Task<string?> GetBaseDcAsync();
 
-    public Task<string> GetDomainAsync();
+    public Task<string?> GetDomainAsync();
 
-    public Task<string> GetUserNameAsync();
+    public Task<string?> GetUserNameAsync();
 
-    public Task<string> GetPasswordAsync();
+    public Task<string?> GetPasswordAsync();
 }

framework/src/Volo.Abp.Ldap/Volo.Abp.Ldap.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Ldap</AssemblyName>
     <PackageId>Volo.Abp.Ldap</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Ldap/Volo/Abp/Ldap/LdapSettingProvider.cs

@@ -14,7 +14,7 @@ public class LdapSettingProvider : ILdapSettingProvider, ITransientDependency
         SettingProvider = settingProvider;
     }
 
-    public async Task<string> GetServerHostAsync()
+    public async Task<string?> GetServerHostAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.ServerHost);
     }
@@ -24,22 +24,22 @@ public class LdapSettingProvider : ILdapSettingProvider, ITransientDependency
         return (await SettingProvider.GetOrNullAsync(LdapSettingNames.ServerPort))?.To<int>() ?? default;
     }
 
-    public async Task<string> GetBaseDcAsync()
+    public async Task<string?> GetBaseDcAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.BaseDc);
     }
 
-    public async Task<string> GetDomainAsync()
+    public async Task<string?> GetDomainAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.Domain);
     }
 
-    public async Task<string> GetUserNameAsync()
+    public async Task<string?> GetUserNameAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.UserName);
     }
 
-    public async Task<string> GetPasswordAsync()
+    public async Task<string?> GetPasswordAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.Password);
     }

framework/src/Volo.Abp.Localization.Abstractions/Microsoft/Extensions/Localization/AbpStringLocalizerFactoryExtensions.cs

@@ -6,15 +6,13 @@ namespace Microsoft.Extensions.Localization;
 
 public static class AbpStringLocalizerFactoryExtensions
 {
-    [CanBeNull]
-    public static IStringLocalizer CreateDefaultOrNull(this IStringLocalizerFactory localizerFactory)
+    public static IStringLocalizer? CreateDefaultOrNull(this IStringLocalizerFactory localizerFactory)
     {
         return (localizerFactory as IAbpStringLocalizerFactory)
             ?.CreateDefaultOrNull();
     }
 
-    [CanBeNull]
-    public static IStringLocalizer CreateByResourceNameOrNull(
+    public static IStringLocalizer? CreateByResourceNameOrNull(
         this IStringLocalizerFactory localizerFactory,
         string resourceName)
     {
@@ -36,8 +34,7 @@ public static class AbpStringLocalizerFactoryExtensions
         return localizer;
     }
     
-    [ItemCanBeNull]
-    public static async Task<IStringLocalizer> CreateByResourceNameOrNullAsync(
+    public static async Task<IStringLocalizer?> CreateByResourceNameOrNullAsync(
         this IStringLocalizerFactory localizerFactory,
         string resourceName)
     {

framework/src/Volo.Abp.Localization.Abstractions/Microsoft/Extensions/Localization/IAbpStringLocalizerFactory.cs

@@ -5,12 +5,9 @@ namespace Microsoft.Extensions.Localization;
 
 public interface IAbpStringLocalizerFactory
 {
-    [CanBeNull]
-    IStringLocalizer CreateDefaultOrNull();
+    IStringLocalizer? CreateDefaultOrNull();
 
-    [CanBeNull]
-    IStringLocalizer CreateByResourceNameOrNull([NotNull] string resourceName);
+    IStringLocalizer? CreateByResourceNameOrNull([NotNull] string resourceName);
     
-    [ItemCanBeNull]
-    Task<IStringLocalizer> CreateByResourceNameOrNullAsync([NotNull] string resourceName);
+    Task<IStringLocalizer?> CreateByResourceNameOrNullAsync([NotNull] string resourceName);
 }

framework/src/Volo.Abp.Localization.Abstractions/Volo.Abp.Localization.Abstractions.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Localization.Abstractions</AssemblyName>
     <PackageId>Volo.Abp.Localization.Abstractions</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Localization.Abstractions/Volo/Abp/Localization/HasNameWithLocalizableDisplayNameExtensions.cs

@@ -10,7 +10,7 @@ public static class HasNameWithLocalizableDisplayNameExtensions
     public static string GetLocalizedDisplayName(
         [NotNull] this IHasNameWithLocalizableDisplayName source,
         [NotNull] IStringLocalizerFactory stringLocalizerFactory,
-        [CanBeNull] string localizationNamePrefix = "DisplayName:")
+        string? localizationNamePrefix = "DisplayName:")
     {
         if (source.DisplayName != null)
         {

framework/src/Volo.Abp.Localization.Abstractions/Volo/Abp/Localization/IHasNameWithLocalizableDisplayName.cs

@@ -7,6 +7,5 @@ public interface IHasNameWithLocalizableDisplayName
     [NotNull]
     public string Name { get; }
 
-    [CanBeNull]
-    public ILocalizableString DisplayName { get; }
+    public ILocalizableString? DisplayName { get; }
 }

framework/src/Volo.Abp.Localization.Abstractions/Volo/Abp/Localization/LocalizableString.cs

@@ -7,16 +7,14 @@ namespace Volo.Abp.Localization;
 
 public class LocalizableString : ILocalizableString, IAsyncLocalizableString
 {
-    [CanBeNull]
-    public string ResourceName { get; }
+    public string? ResourceName { get; }
     
-    [CanBeNull]
-    public Type ResourceType { get; }
+    public Type? ResourceType { get; }
 
     [NotNull]
     public string Name { get; }
 
-    public LocalizableString([CanBeNull] Type resourceType, [NotNull] string name)
+    public LocalizableString(Type? resourceType, [NotNull] string name)
     {
         Name = Check.NotNullOrEmpty(name, nameof(name));
         ResourceType = resourceType;
@@ -27,7 +25,7 @@ public class LocalizableString : ILocalizableString, IAsyncLocalizableString
         }
     }
 
-    public LocalizableString([NotNull] string name, [CanBeNull] string resourceName = null)
+    public LocalizableString([NotNull] string name, string? resourceName = null)
     {
         Name = Check.NotNullOrEmpty(name, nameof(name));
         ResourceName = resourceName;
@@ -79,7 +77,7 @@ public class LocalizableString : ILocalizableString, IAsyncLocalizableString
         return result;
     }
 
-    private IStringLocalizer CreateStringLocalizerOrNull(IStringLocalizerFactory stringLocalizerFactory)
+    private IStringLocalizer? CreateStringLocalizerOrNull(IStringLocalizerFactory stringLocalizerFactory)
     {
         if (ResourceType != null)
         {
@@ -98,7 +96,7 @@ public class LocalizableString : ILocalizableString, IAsyncLocalizableString
         return stringLocalizerFactory.CreateDefaultOrNull();
     }
     
-    private async Task<IStringLocalizer> CreateStringLocalizerOrNullAsync(IStringLocalizerFactory stringLocalizerFactory)
+    private async Task<IStringLocalizer?> CreateStringLocalizerOrNullAsync(IStringLocalizerFactory stringLocalizerFactory)
     {
         if (ResourceType != null)
         {
@@ -127,7 +125,7 @@ public class LocalizableString : ILocalizableString, IAsyncLocalizableString
         return new LocalizableString(resourceType, name);
     }
     
-    public static LocalizableString Create([NotNull] string name, [CanBeNull] string resourceName = null)
+    public static LocalizableString Create([NotNull] string name, string? resourceName = null)
     {
         return new LocalizableString(name, resourceName);
     }

framework/src/Volo.Abp.Localization.Abstractions/Volo/Abp/Localization/LocalizationResourceNameAttribute.cs

@@ -12,7 +12,7 @@ public class LocalizationResourceNameAttribute : Attribute
         Name = name;
     }
 
-    public static LocalizationResourceNameAttribute GetOrNull(Type resourceType)
+    public static LocalizationResourceNameAttribute? GetOrNull(Type resourceType)
     {
         return resourceType
             .GetCustomAttributes(true)
@@ -22,6 +22,6 @@ public class LocalizationResourceNameAttribute : Attribute
 
     public static string GetName(Type resourceType)
     {
-        return GetOrNull(resourceType)?.Name ?? resourceType.FullName;
+        return (GetOrNull(resourceType)?.Name ?? resourceType.FullName)!;
     }
 }

framework/src/Volo.Abp.Localization/Volo.Abp.Localization.csproj

@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Localization</AssemblyName>
     <PackageId>Volo.Abp.Localization</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/AbpDictionaryBasedStringLocalizer.cs

@@ -118,7 +118,7 @@ public class AbpDictionaryBasedStringLocalizer : IAbpStringLocalizer
         return value;
     }
 
-    protected virtual LocalizedString GetLocalizedStringOrNull(
+    protected virtual LocalizedString? GetLocalizedStringOrNull(
         string name,
         string cultureName,
         bool tryDefaults = true)
@@ -153,7 +153,7 @@ public class AbpDictionaryBasedStringLocalizer : IAbpStringLocalizer
             //Try to get from default language
             if (!Resource.DefaultCultureName.IsNullOrEmpty())
             {
-                var strDefault = Resource.Contributors.GetOrNull(Resource.DefaultCultureName, name);
+                var strDefault = Resource.Contributors.GetOrNull(Resource.DefaultCultureName!, name);
                 if (strDefault != null)
                 {
                     return strDefault;
@@ -208,7 +208,7 @@ public class AbpDictionaryBasedStringLocalizer : IAbpStringLocalizer
             //Fill all strings from default culture
             if (!Resource.DefaultCultureName.IsNullOrEmpty())
             {
-                Resource.Contributors.Fill(Resource.DefaultCultureName, allStrings, includeDynamicContributors);
+                Resource.Contributors.Fill(Resource.DefaultCultureName!, allStrings, includeDynamicContributors);
             }
 
             //Overwrite all strings from the language based on country culture
@@ -268,7 +268,7 @@ public class AbpDictionaryBasedStringLocalizer : IAbpStringLocalizer
             if (!Resource.DefaultCultureName.IsNullOrEmpty())
             {
                 await Resource.Contributors.FillAsync(
-                    Resource.DefaultCultureName,
+                    Resource.DefaultCultureName!,
                     allStrings,
                     includeDynamicContributors
                 );

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/AbpEnumLocalizer.cs

@@ -19,14 +19,14 @@ public class AbpEnumLocalizer : IAbpEnumLocalizer, ITransientDependency
         return GetStringInternal(enumType, enumValue, StringLocalizerFactory.CreateDefaultOrNull());
     }
 
-    public virtual string GetString(Type enumType, object enumValue, params IStringLocalizer[] specifyLocalizers)
+    public virtual string GetString(Type enumType, object enumValue, params IStringLocalizer?[] specifyLocalizers)
     {
         return GetStringInternal(enumType, enumValue, specifyLocalizers);
     }
 
-    protected virtual string GetStringInternal(Type enumType, object enumValue, params IStringLocalizer[] specifyLocalizers)
+    protected virtual string GetStringInternal(Type enumType, object enumValue, params IStringLocalizer?[] specifyLocalizers)
     {
-        var memberName = enumType.GetEnumName(enumValue);
+        var memberName = enumType.GetEnumName(enumValue)!;
         var localizedString = GetStringOrNull(
             specifyLocalizers,
             new[]
@@ -42,7 +42,7 @@ public class AbpEnumLocalizer : IAbpEnumLocalizer, ITransientDependency
         return localizedString ?? memberName;
     }
 
-    protected virtual string GetStringOrNull(IStringLocalizer[] localizers, IEnumerable<string> keys)
+    protected virtual string? GetStringOrNull(IStringLocalizer?[] localizers, IEnumerable<string> keys)
     {
         foreach (var key in keys)
         {

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/AbpLocalizationOptions.cs

@@ -11,7 +11,7 @@ public class AbpLocalizationOptions
     /// <summary>
     /// Used as the default resource when resource was not specified on a localization operation.
     /// </summary>
-    public Type DefaultResourceType { get; set; }
+    public Type? DefaultResourceType { get; set; }
 
     public ITypeList<ILocalizationResourceContributor> GlobalContributors { get; }
 

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/AbpStringLocalizerExtensions.cs

@@ -35,7 +35,7 @@ public static class AbpStringLocalizerExtensions
             throw new AbpException($"Could not find the _localizer field inside the {typeof(StringLocalizer<>).FullName} class. Probably its name has changed. Please report this issue to the ABP framework.");
         }
 
-        return localizerField.GetValue(stringLocalizer) as IStringLocalizer;
+        return (localizerField.GetValue(stringLocalizer) as IStringLocalizer)!;
     }
 
     public static IEnumerable<LocalizedString> GetAllStrings(

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/AbpStringLocalizerFactory.cs

@@ -52,12 +52,12 @@ public class AbpStringLocalizerFactory : IStringLocalizerFactory, IAbpStringLoca
         return CreateInternal(resource.ResourceName, resource, lockCache);
     }
     
-    public IStringLocalizer CreateByResourceNameOrNull(string resourceName)
+    public IStringLocalizer? CreateByResourceNameOrNull(string resourceName)
     {
         return CreateByResourceNameOrNullInternal(resourceName, lockCache: true);
     }
     
-    private IStringLocalizer CreateByResourceNameOrNullInternal(
+    private IStringLocalizer? CreateByResourceNameOrNullInternal(
         string resourceName,
         bool lockCache)
     {
@@ -74,12 +74,12 @@ public class AbpStringLocalizerFactory : IStringLocalizerFactory, IAbpStringLoca
         return CreateInternal(resourceName, resource, lockCache);
     }
 
-    public Task<IStringLocalizer> CreateByResourceNameOrNullAsync(string resourceName)
+    public Task<IStringLocalizer?> CreateByResourceNameOrNullAsync(string resourceName)
     {
         return CreateByResourceNameOrNullInternalAsync(resourceName, lockCache: true);
     }
     
-    private async Task<IStringLocalizer> CreateByResourceNameOrNullInternalAsync(
+    private async Task<IStringLocalizer?> CreateByResourceNameOrNullInternalAsync(
         string resourceName,
         bool lockCache)
     {
@@ -175,7 +175,7 @@ public class AbpStringLocalizerFactory : IStringLocalizerFactory, IAbpStringLoca
         {
             resource.Contributors.Add(
                 Activator
-                    .CreateInstance(globalContributorType)
+                    .CreateInstance(globalContributorType)!
                     .As<ILocalizationResourceContributor>()
             );
         }
@@ -194,7 +194,7 @@ public class AbpStringLocalizerFactory : IStringLocalizerFactory, IAbpStringLoca
                     .BaseResourceNames
                     .Select(x => CreateByResourceNameOrNullInternal(x, lockCache: false))
                     .Where(x => x != null)
-                    .ToList(),
+                    .ToList()!,
                 AbpLocalizationOptions
             )
         );
@@ -206,7 +206,7 @@ public class AbpStringLocalizerFactory : IStringLocalizerFactory, IAbpStringLoca
         {
             resource.Contributors.Add(
                 Activator
-                    .CreateInstance(globalContributorType)
+                    .CreateInstance(globalContributorType)!
                     .As<ILocalizationResourceContributor>()
             );
         }
@@ -259,7 +259,7 @@ public class AbpStringLocalizerFactory : IStringLocalizerFactory, IAbpStringLoca
         }
     }
 
-    public IStringLocalizer CreateDefaultOrNull()
+    public IStringLocalizer? CreateDefaultOrNull()
     {
         if (AbpLocalizationOptions.DefaultResourceType == null)
         {

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/External/IExternalLocalizationStore.cs

@@ -5,11 +5,9 @@ namespace Volo.Abp.Localization.External;
 
 public interface IExternalLocalizationStore
 {
-    [CanBeNull] 
-    LocalizationResourceBase GetResourceOrNull([NotNull] string resourceName);
+    LocalizationResourceBase? GetResourceOrNull([NotNull] string resourceName);
     
-    [ItemCanBeNull] 
-    Task<LocalizationResourceBase> GetResourceOrNullAsync([NotNull] string resourceName);
+    Task<LocalizationResourceBase?> GetResourceOrNullAsync([NotNull] string resourceName);
     
     Task<string[]> GetResourceNamesAsync();
     

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/External/NullExternalLocalizationStore.cs

@@ -6,14 +6,14 @@ namespace Volo.Abp.Localization.External;
 
 public class NullExternalLocalizationStore : IExternalLocalizationStore, ISingletonDependency
 {
-    public LocalizationResourceBase GetResourceOrNull(string resourceName)
+    public LocalizationResourceBase? GetResourceOrNull(string resourceName)
     {
         return null;
     }
 
-    public Task<LocalizationResourceBase> GetResourceOrNullAsync(string resourceName)
+    public Task<LocalizationResourceBase?> GetResourceOrNullAsync(string resourceName)
     {
-        return Task.FromResult<LocalizationResourceBase>(null);
+        return Task.FromResult<LocalizationResourceBase?>(null);
     }
 
     public Task<string[]> GetResourceNamesAsync()

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/ILanguageInfo.cs

@@ -8,5 +8,5 @@ public interface ILanguageInfo
 
     string DisplayName { get; }
 
-    string FlagIcon { get; }
+    string? FlagIcon { get; }
 }

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/ILocalizableStringSerializer.cs

@@ -2,7 +2,7 @@
 
 public interface ILocalizableStringSerializer
 {
-    string Serialize(ILocalizableString localizableString);
+    string? Serialize(ILocalizableString localizableString);
     
     ILocalizableString Deserialize(string value);
 }

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/ILocalizationDictionary.cs

@@ -10,7 +10,7 @@ public interface ILocalizationDictionary
 {
     string CultureName { get; }
 
-    LocalizedString GetOrNull(string name);
+    LocalizedString? GetOrNull(string name);
 
     void Fill(Dictionary<string, LocalizedString> dictionary);
 }

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/ILocalizationResourceContributor.cs

@@ -10,7 +10,7 @@ public interface ILocalizationResourceContributor
     
     void Initialize(LocalizationResourceInitializationContext context);
 
-    LocalizedString GetOrNull(string cultureName, string name);
+    LocalizedString? GetOrNull(string cultureName, string name);
 
     void Fill(string cultureName, Dictionary<string, LocalizedString> dictionary);
 

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/Json/JsonLocalizationDictionaryBuilder.cs

@@ -2,7 +2,6 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Text.Json;
-using JetBrains.Annotations;
 using Microsoft.Extensions.Localization;
 
 namespace Volo.Abp.Localization.Json;
@@ -13,8 +12,7 @@ public static class JsonLocalizationDictionaryBuilder
     ///     Builds an <see cref="JsonLocalizationDictionaryBuilder" /> from given file.
     /// </summary>
     /// <param name="filePath">Path of the file</param>
-    [CanBeNull]
-    public static ILocalizationDictionary BuildFromFile(string filePath)
+    public static ILocalizationDictionary? BuildFromFile(string filePath)
     {
         try
         {
@@ -38,10 +36,9 @@ public static class JsonLocalizationDictionaryBuilder
     ///     Builds an <see cref="JsonLocalizationDictionaryBuilder" /> from given json string.
     /// </summary>
     /// <param name="jsonString">Json string</param>
-    [CanBeNull]
-    public static ILocalizationDictionary BuildFromJsonString(string jsonString)
+    public static ILocalizationDictionary? BuildFromJsonString(string jsonString)
     {
-        JsonLocalizationFile jsonFile;
+        JsonLocalizationFile? jsonFile;
         try
         {
             jsonFile = JsonSerializer.Deserialize<JsonLocalizationFile>(jsonString, DeserializeOptions);
@@ -50,6 +47,11 @@ public static class JsonLocalizationDictionaryBuilder
         {
             throw new AbpException("Can not parse json string. " + ex.Message);
         }
+
+        if (jsonFile == null)
+        {
+            return null;
+        }
         
         var cultureCode = jsonFile.Culture;
         if (string.IsNullOrEmpty(cultureCode))

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/Json/JsonLocalizationFile.cs

@@ -7,7 +7,7 @@ public class JsonLocalizationFile
     /// <summary>
     /// Culture name; eg : en , en-us, zh-CN
     /// </summary>
-    public string Culture { get; set; }
+    public string Culture { get; set; } = default!;
 
     public Dictionary<string, string> Texts { get; set; }
 

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LanguageInfo.cs

@@ -8,19 +8,18 @@ namespace Volo.Abp.Localization;
 public class LanguageInfo : ILanguageInfo
 {
     [NotNull]
-    public virtual string CultureName { get; protected set; }
+    public virtual string CultureName { get; protected set; } = default!;
 
     [NotNull]
-    public virtual string UiCultureName { get; protected set; }
+    public virtual string UiCultureName { get; protected set; } = default!;
 
     [NotNull]
-    public virtual string DisplayName { get; protected set; }
+    public virtual string DisplayName { get; protected set; } = default!;
 
     [NotNull]
-    public virtual string TwoLetterISOLanguageName { get; protected set; }
+    public virtual string TwoLetterISOLanguageName { get; protected set; } = default!;
 
-    [CanBeNull]
-    public virtual string FlagIcon { get; set; }
+    public virtual string? FlagIcon { get; set; }
 
     
     protected LanguageInfo()
@@ -30,30 +29,30 @@ public class LanguageInfo : ILanguageInfo
 
     public LanguageInfo(
         string cultureName,
-        string uiCultureName = null,
-        string displayName = null,
-        string flagIcon = null)
+        string? uiCultureName = null,
+        string? displayName = null,
+        string? flagIcon = null)
     {
         ChangeCultureInternal(cultureName, uiCultureName, displayName);
         FlagIcon = flagIcon;
     }
 
-    public virtual void ChangeCulture(string cultureName, string uiCultureName = null, string displayName = null)
+    public virtual void ChangeCulture(string cultureName, string? uiCultureName = null, string? displayName = null)
     {
         ChangeCultureInternal(cultureName, uiCultureName, displayName);
     }
 
-    private void ChangeCultureInternal(string cultureName, string uiCultureName, string displayName)
+    private void ChangeCultureInternal(string cultureName, string? uiCultureName, string? displayName)
     {
         CultureName = Check.NotNullOrWhiteSpace(cultureName, nameof(cultureName));
 
-        UiCultureName = !uiCultureName.IsNullOrWhiteSpace()
+        UiCultureName = (!uiCultureName.IsNullOrWhiteSpace()
             ? uiCultureName
-            : cultureName;
+            : cultureName)!;
 
-        DisplayName = !displayName.IsNullOrWhiteSpace()
+        DisplayName = (!displayName.IsNullOrWhiteSpace()
             ? displayName
-            : cultureName;
+            : cultureName)!;
         
         TwoLetterISOLanguageName = new CultureInfo(cultureName)
             .TwoLetterISOLanguageName;

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LanguageInfoExtensions.cs

@@ -6,10 +6,10 @@ namespace Volo.Abp.Localization;
 
 public static class LanguageInfoExtensions
 {
-    public static T FindByCulture<T>(
+    public static T? FindByCulture<T>(
         [NotNull] this IEnumerable<T> languages,
         [NotNull] string cultureName,
-        [CanBeNull] string uiCultureName = null)
+        string? uiCultureName = null)
     where T : class, ILanguageInfo
     {
         if (uiCultureName == null)

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LocalizableStringSerializer.cs

@@ -13,7 +13,7 @@ public class LocalizableStringSerializer : ILocalizableStringSerializer, ITransi
         LocalizationOptions = localizationOptions.Value;
     }
 
-    public virtual string Serialize(ILocalizableString localizableString)
+    public virtual string? Serialize(ILocalizableString? localizableString)
     {
         if (localizableString == null)
         {

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LocalizationResource.cs

@@ -12,8 +12,8 @@ public class LocalizationResource : LocalizationResourceBase
 
     public LocalizationResource(
         [NotNull] Type resourceType,
-        [CanBeNull] string defaultCultureName = null,
-        [CanBeNull] ILocalizationResourceContributor initialContributor = null)
+        string? defaultCultureName = null,
+        ILocalizationResourceContributor? initialContributor = null)
         : base(
             LocalizationResourceNameAttribute.GetName(resourceType),
             defaultCultureName,

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LocalizationResourceBase.cs

@@ -10,16 +10,15 @@ public abstract class LocalizationResourceBase
     
     public List<string> BaseResourceNames { get; }
     
-    [CanBeNull]
-    public string DefaultCultureName { get; set; }
+    public string? DefaultCultureName { get; set; }
     
     [NotNull]
     public LocalizationResourceContributorList Contributors { get; }
 
     public LocalizationResourceBase(
         [NotNull] string resourceName,
-        [CanBeNull] string defaultCultureName = null,
-        [CanBeNull] ILocalizationResourceContributor initialContributor = null)
+        string? defaultCultureName = null,
+        ILocalizationResourceContributor? initialContributor = null)
     {
         ResourceName = Check.NotNullOrWhiteSpace(resourceName, nameof(resourceName));
         DefaultCultureName = defaultCultureName;

framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LocalizationResourceContributorList.cs

@@ -7,7 +7,7 @@ namespace Volo.Abp.Localization;
 
 public class LocalizationResourceContributorList : List<ILocalizationResourceContributor>
 {
-    public LocalizedString GetOrNull(
+    public LocalizedString? GetOrNull(
         string cultureName,
         string name,
         bool includeDynamicContributors = true)