Enable nullable annotations for Volo.Abp.Core

framework/src/Volo.Abp.Core/Microsoft/Extensions/Configuration/AbpConfigurationBuilderOptions.cs

@@ -8,13 +8,13 @@ public class AbpConfigurationBuilderOptions
     /// Used to set assembly which is used to get the user secret id for the application.
     /// Use this or <see cref="UserSecretsId"/> (higher priority)
     /// </summary>
-    public Assembly UserSecretsAssembly { get; set; }
+    public Assembly? UserSecretsAssembly { get; set; }
 
     /// <summary>
     /// Used to set user secret id for the application.
     /// Use this (higher priority) or <see cref="UserSecretsAssembly"/>
     /// </summary>
-    public string UserSecretsId { get; set; }
+    public string? UserSecretsId { get; set; }
 
     /// <summary>
     /// Default value: "appsettings".
@@ -34,20 +34,20 @@ public class AbpConfigurationBuilderOptions
     /// <summary>
     /// Environment name. Generally used "Development", "Staging" or "Production".
     /// </summary>
-    public string EnvironmentName { get; set; }
+    public string? EnvironmentName { get; set; }
 
     /// <summary>
     /// Base path to read the configuration file indicated by <see cref="FileName"/>.
     /// </summary>
-    public string BasePath { get; set; }
+    public string? BasePath { get; set; }
 
     /// <summary>
     /// Prefix for the environment variables.
     /// </summary>
-    public string EnvironmentVariablesPrefix { get; set; }
+    public string? EnvironmentVariablesPrefix { get; set; }
 
     /// <summary>
     /// Command line arguments.
     /// </summary>
-    public string[] CommandLineArgs { get; set; }
+    public string[]? CommandLineArgs { get; set; }
 }

framework/src/Volo.Abp.Core/Microsoft/Extensions/Configuration/ConfigurationHelper.cs

@@ -6,8 +6,8 @@ namespace Microsoft.Extensions.Configuration;
 public static class ConfigurationHelper
 {
     public static IConfigurationRoot BuildConfiguration(
-        AbpConfigurationBuilderOptions options = null,
+        AbpConfigurationBuilderOptions? options = null,
-        Action<IConfigurationBuilder> builderAction = null)
+        Action<IConfigurationBuilder>? builderAction = null)
     {
         options ??= new AbpConfigurationBuilderOptions();
 
@@ -17,7 +17,7 @@ public static class ConfigurationHelper
         }
 
         var builder = new ConfigurationBuilder()
-            .SetBasePath(options.BasePath)
+            .SetBasePath(options.BasePath!)
             .AddJsonFile(options.FileName + ".json", optional: options.Optional, reloadOnChange: options.ReloadOnChange);
 
         if (!options.EnvironmentName.IsNullOrEmpty())

framework/src/Volo.Abp.Core/Microsoft/Extensions/DependencyInjection/ServiceCollectionApplicationExtensions.cs

@@ -10,7 +10,7 @@ public static class ServiceCollectionApplicationExtensions
 {
     public static IAbpApplicationWithExternalServiceProvider AddApplication<TStartupModule>(
         [NotNull] this IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
         where TStartupModule : IAbpModule
     {
         return AbpApplicationFactory.Create<TStartupModule>(services, optionsAction);
@@ -19,14 +19,14 @@ public static class ServiceCollectionApplicationExtensions
     public static IAbpApplicationWithExternalServiceProvider AddApplication(
         [NotNull] this IServiceCollection services,
         [NotNull] Type startupModuleType,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
     {
         return AbpApplicationFactory.Create(startupModuleType, services, optionsAction);
     }
 
     public async static Task<IAbpApplicationWithExternalServiceProvider> AddApplicationAsync<TStartupModule>(
         [NotNull] this IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
         where TStartupModule : IAbpModule
     {
         return await AbpApplicationFactory.CreateAsync<TStartupModule>(services,  optionsAction);
@@ -35,13 +35,12 @@ public static class ServiceCollectionApplicationExtensions
     public async static Task<IAbpApplicationWithExternalServiceProvider> AddApplicationAsync(
         [NotNull] this IServiceCollection services,
         [NotNull] Type startupModuleType,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
     {
         return await AbpApplicationFactory.CreateAsync(startupModuleType, services, optionsAction);
     }
 
-    [CanBeNull]
+    public static string? GetApplicationName(this IServiceCollection services)
-    public static string GetApplicationName(this IServiceCollection services)
     {
         return services.GetSingletonInstance<IApplicationInfoAccessor>().ApplicationName;
     }

framework/src/Volo.Abp.Core/Microsoft/Extensions/DependencyInjection/ServiceCollectionCommonExtensions.cs

@@ -24,9 +24,9 @@ public static class ServiceCollectionCommonExtensions
         return services.GetSingletonInstance<ITypeFinder>();
     }
 
-    public static T GetSingletonInstanceOrNull<T>(this IServiceCollection services)
+    public static T? GetSingletonInstanceOrNull<T>(this IServiceCollection services)
     {
-        return (T)services
+        return (T?)services
             .FirstOrDefault(d => d.ServiceType == typeof(T))
             ?.ImplementationInstance;
     }
@@ -65,13 +65,13 @@ public static class ServiceCollectionCommonExtensions
                 .GetMethods()
                 .Single(m => m.Name == nameof(BuildServiceProviderFromFactory) && m.IsGenericMethod)
                 .MakeGenericMethod(containerBuilderType)
-                .Invoke(null, new object[] { services, null });
+                .Invoke(null, new object?[] { services, null })!;
         }
 
         return services.BuildServiceProvider();
     }
 
-    public static IServiceProvider BuildServiceProviderFromFactory<TContainerBuilder>([NotNull] this IServiceCollection services, Action<TContainerBuilder> builderAction = null)
+    public static IServiceProvider BuildServiceProviderFromFactory<TContainerBuilder>([NotNull] this IServiceCollection services, Action<TContainerBuilder>? builderAction = null) where TContainerBuilder : notnull
     {
         Check.NotNull(services, nameof(services));
 
@@ -90,7 +90,7 @@ public static class ServiceCollectionCommonExtensions
     /// Resolves a dependency using given <see cref="IServiceCollection"/>.
     /// This method should be used only after dependency injection registration phase completed.
     /// </summary>
-    internal static T GetService<T>(this IServiceCollection services)
+    internal static T? GetService<T>(this IServiceCollection services)
     {
         return services
             .GetSingletonInstance<IAbpApplication>()
@@ -102,7 +102,7 @@ public static class ServiceCollectionCommonExtensions
     /// Resolves a dependency using given <see cref="IServiceCollection"/>.
     /// This method should be used only after dependency injection registration phase completed.
     /// </summary>
-    internal static object GetService(this IServiceCollection services, Type type)
+    internal static object? GetService(this IServiceCollection services, Type type)
     {
         return services
             .GetSingletonInstance<IAbpApplication>()
@@ -115,7 +115,7 @@ public static class ServiceCollectionCommonExtensions
     /// Throws exception if service is not registered.
     /// This method should be used only after dependency injection registration phase completed.
     /// </summary>
-    public static T GetRequiredService<T>(this IServiceCollection services)
+    public static T GetRequiredService<T>(this IServiceCollection services) where T : notnull
     {
         return services
             .GetSingletonInstance<IAbpApplication>()
@@ -140,25 +140,25 @@ public static class ServiceCollectionCommonExtensions
     /// Returns a <see cref="Lazy{T}"/> to resolve a service from given <see cref="IServiceCollection"/>
     /// once dependency injection registration phase completed.
     /// </summary>
-    public static Lazy<T> GetServiceLazy<T>(this IServiceCollection services)
+    public static Lazy<T?> GetServiceLazy<T>(this IServiceCollection services)
     {
-        return new Lazy<T>(services.GetService<T>, true);
+        return new Lazy<T?>(services.GetService<T>, true);
     }
 
     /// <summary>
     /// Returns a <see cref="Lazy{T}"/> to resolve a service from given <see cref="IServiceCollection"/>
     /// once dependency injection registration phase completed.
     /// </summary>
-    public static Lazy<object> GetServiceLazy(this IServiceCollection services, Type type)
+    public static Lazy<object?> GetServiceLazy(this IServiceCollection services, Type type)
     {
-        return new Lazy<object>(() => services.GetService(type), true);
+        return new Lazy<object?>(() => services.GetService(type), true);
     }
 
     /// <summary>
     /// Returns a <see cref="Lazy{T}"/> to resolve a service from given <see cref="IServiceCollection"/>
     /// once dependency injection registration phase completed.
     /// </summary>
-    public static Lazy<T> GetRequiredServiceLazy<T>(this IServiceCollection services)
+    public static Lazy<T> GetRequiredServiceLazy<T>(this IServiceCollection services) where T : notnull
     {
         return new Lazy<T>(services.GetRequiredService<T>, true);
     }
@@ -172,7 +172,7 @@ public static class ServiceCollectionCommonExtensions
         return new Lazy<object>(() => services.GetRequiredService(type), true);
     }
 
-    public static IServiceProvider GetServiceProviderOrNull(this IServiceCollection services)
+    public static IServiceProvider? GetServiceProviderOrNull(this IServiceCollection services)
     {
         return services.GetObjectOrNull<IServiceProvider>();
     }

framework/src/Volo.Abp.Core/Microsoft/Extensions/DependencyInjection/ServiceCollectionConfigurationExtensions.cs

@@ -21,7 +21,7 @@ public static class ServiceCollectionConfigurationExtensions
     }
     
     [CanBeNull]
-    public static IConfiguration GetConfigurationOrNull(this IServiceCollection services)
+    public static IConfiguration? GetConfigurationOrNull(this IServiceCollection services)
     {
         var hostBuilderContext = services.GetSingletonInstanceOrNull<HostBuilderContext>();
         if (hostBuilderContext?.Configuration != null)

framework/src/Volo.Abp.Core/Microsoft/Extensions/DependencyInjection/ServiceCollectionObjectAccessorExtensions.cs

@@ -40,7 +40,7 @@ public static class ServiceCollectionObjectAccessorExtensions
         return accessor;
     }
 
-    public static T GetObjectOrNull<T>(this IServiceCollection services)
+    public static T? GetObjectOrNull<T>(this IServiceCollection services)
         where T : class
     {
         return services.GetSingletonInstanceOrNull<IObjectAccessor<T>>()?.Value;

framework/src/Volo.Abp.Core/Microsoft/Extensions/Logging/AbpLoggerExtensions.cs

@@ -83,7 +83,7 @@ public static class AbpLoggerExtensions
 
     private static void LogData(ILogger logger, Exception exception, LogLevel logLevel)
     {
-        if (exception.Data == null || exception.Data.Count <= 0)
+        if (exception.Data.Count <= 0)
         {
             return;
         }
@@ -102,23 +102,22 @@ public static class AbpLoggerExtensions
     {
         var loggingExceptions = new List<IExceptionWithSelfLogging>();
 
-        if (exception is IExceptionWithSelfLogging)
+        if (exception is IExceptionWithSelfLogging logging)
         {
-            loggingExceptions.Add(exception as IExceptionWithSelfLogging);
+            loggingExceptions.Add(logging);
         }
-        else if (exception is AggregateException && exception.InnerException != null)
+        else if (exception is AggregateException aggException && aggException.InnerException != null)
         {
-            var aggException = exception as AggregateException;
+            if (aggException.InnerException is IExceptionWithSelfLogging selfLogging)
-            if (aggException.InnerException is IExceptionWithSelfLogging)
             {
-                loggingExceptions.Add(aggException.InnerException as IExceptionWithSelfLogging);
+                loggingExceptions.Add(selfLogging);
             }
 
             foreach (var innerException in aggException.InnerExceptions)
             {
-                if (innerException is IExceptionWithSelfLogging)
+                if (innerException is IExceptionWithSelfLogging withSelfLogging)
                 {
-                    loggingExceptions.AddIfNotContains(innerException as IExceptionWithSelfLogging);
+                    loggingExceptions.AddIfNotContains(withSelfLogging);
                 }
             }
         }

framework/src/Volo.Abp.Core/System/AbpObjectExtensions.cs

@@ -36,7 +36,7 @@ public static class AbpObjectExtensions
     {
         if (typeof(T) == typeof(Guid))
         {
-            return (T)TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(obj.ToString());
+            return (T)TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(obj.ToString()!)!;
         }
 
         return (T)Convert.ChangeType(obj, typeof(T), CultureInfo.InvariantCulture);

framework/src/Volo.Abp.Core/System/AbpStringExtensions.cs

@@ -47,7 +47,7 @@ public static class AbpStringExtensions
     /// Indicates whether this string is null or an System.String.Empty string.
     /// </summary>
     [ContractAnnotation("str:null => true")]
-    public static bool IsNullOrEmpty(this string str)
+    public static bool IsNullOrEmpty(this string? str)
     {
         return string.IsNullOrEmpty(str);
     }
@@ -56,7 +56,7 @@ public static class AbpStringExtensions
     /// indicates whether this string is null, empty, or consists only of white-space characters.
     /// </summary>
     [ContractAnnotation("str:null => true")]
-    public static bool IsNullOrWhiteSpace(this string str)
+    public static bool IsNullOrWhiteSpace(this string? str)
     {
         return string.IsNullOrWhiteSpace(str);
     }
@@ -482,7 +482,7 @@ public static class AbpStringExtensions
     /// Gets a substring of a string from beginning of the string if it exceeds maximum length.
     /// </summary>
     [ContractAnnotation("null <= str:null")]
-    public static string Truncate(this string str, int maxLength)
+    public static string? Truncate(this string? str, int maxLength)
     {
         if (str == null)
         {
@@ -501,7 +501,7 @@ public static class AbpStringExtensions
     /// Gets a substring of a string from Ending of the string if it exceeds maximum length.
     /// </summary>
     [ContractAnnotation("null <= str:null")]
-    public static string TruncateFromBeginning(this string str, int maxLength)
+    public static string? TruncateFromBeginning(this string? str, int maxLength)
     {
         if (str == null)
         {
@@ -522,7 +522,7 @@ public static class AbpStringExtensions
     /// Returning string can not be longer than maxLength.
     /// </summary>
     /// <exception cref="ArgumentNullException">Thrown if <paramref name="str"/> is null</exception>
-    public static string TruncateWithPostfix(this string str, int maxLength)
+    public static string? TruncateWithPostfix(this string? str, int maxLength)
     {
         return TruncateWithPostfix(str, maxLength, "...");
     }
@@ -534,7 +534,7 @@ public static class AbpStringExtensions
     /// </summary>
     /// <exception cref="ArgumentNullException">Thrown if <paramref name="str"/> is null</exception>
     [ContractAnnotation("null <= str:null")]
-    public static string TruncateWithPostfix(this string str, int maxLength, string postfix)
+    public static string? TruncateWithPostfix(this string? str, int maxLength, string postfix)
     {
         if (str == null)
         {

framework/src/Volo.Abp.Core/System/AbpTypeExtensions.cs

@@ -72,9 +72,9 @@ public static class AbpTypeExtensions
 
     private static void AddTypeAndBaseTypesRecursively(
         [NotNull] List<Type> types,
-        [CanBeNull] Type type,
+        Type? type,
         bool includeObject,
-        [CanBeNull] Type stoppingType = null)
+        Type? stoppingType = null)
     {
         if (type == null || type == stoppingType)
         {

framework/src/Volo.Abp.Core/System/Collections/Generic/AbpCollectionExtensions.cs

@@ -13,7 +13,7 @@ public static class AbpCollectionExtensions
     /// Checks whatever given collection object is null or has no item.
     /// </summary>
     [ContractAnnotation("source:null => true")]
-    public static bool IsNullOrEmpty<T>([CanBeNull] this ICollection<T> source)
+    public static bool IsNullOrEmpty<T>(this ICollection<T>? source)
     {
         return source == null || source.Count <= 0;
     }

framework/src/Volo.Abp.Core/System/Collections/Generic/AbpDictionaryExtensions.cs

@@ -16,9 +16,9 @@ public static class AbpDictionaryExtensions
     /// <param name="key">Key</param>
     /// <param name="value">Value of the key (or default value if key not exists)</param>
     /// <returns>True if key does exists in the dictionary</returns>
-    internal static bool TryGetValue<T>(this IDictionary<string, object> dictionary, string key, out T value)
+    internal static bool TryGetValue<T>(this IDictionary<string, object> dictionary, string key, out T? value)
     {
-        object valueObj;
+        object? valueObj;
         if (dictionary.TryGetValue(key, out valueObj) && valueObj is T)
         {
             value = (T)valueObj;
@@ -37,9 +37,9 @@ public static class AbpDictionaryExtensions
     /// <typeparam name="TKey">Type of the key</typeparam>
     /// <typeparam name="TValue">Type of the value</typeparam>
     /// <returns>Value if found, default if can not found.</returns>
-    public static TValue GetOrDefault<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key)
+    public static TValue? GetOrDefault<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key) where TKey : notnull
     {
-        TValue obj;
+        TValue? obj;
         return dictionary.TryGetValue(key, out obj) ? obj : default;
     }
 
@@ -51,7 +51,7 @@ public static class AbpDictionaryExtensions
     /// <typeparam name="TKey">Type of the key</typeparam>
     /// <typeparam name="TValue">Type of the value</typeparam>
     /// <returns>Value if found, default if can not found.</returns>
-    public static TValue GetOrDefault<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key)
+    public static TValue? GetOrDefault<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key)
     {
         return dictionary.TryGetValue(key, out var obj) ? obj : default;
     }
@@ -64,7 +64,7 @@ public static class AbpDictionaryExtensions
     /// <typeparam name="TKey">Type of the key</typeparam>
     /// <typeparam name="TValue">Type of the value</typeparam>
     /// <returns>Value if found, default if can not found.</returns>
-    public static TValue GetOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key)
+    public static TValue? GetOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key)
     {
         return dictionary.TryGetValue(key, out var obj) ? obj : default;
     }
@@ -77,7 +77,7 @@ public static class AbpDictionaryExtensions
     /// <typeparam name="TKey">Type of the key</typeparam>
     /// <typeparam name="TValue">Type of the value</typeparam>
     /// <returns>Value if found, default if can not found.</returns>
-    public static TValue GetOrDefault<TKey, TValue>(this ConcurrentDictionary<TKey, TValue> dictionary, TKey key)
+    public static TValue? GetOrDefault<TKey, TValue>(this ConcurrentDictionary<TKey, TValue> dictionary, TKey key) where TKey : notnull
     {
         return dictionary.TryGetValue(key, out var obj) ? obj : default;
     }
@@ -93,7 +93,7 @@ public static class AbpDictionaryExtensions
     /// <returns>Value if found, default if can not found.</returns>
     public static TValue GetOrAdd<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, Func<TKey, TValue> factory)
     {
-        TValue obj;
+        TValue? obj;
         if (dictionary.TryGetValue(key, out obj))
         {
             return obj;
@@ -125,7 +125,7 @@ public static class AbpDictionaryExtensions
     /// <typeparam name="TKey">Type of the key</typeparam>
     /// <typeparam name="TValue">Type of the value</typeparam>
     /// <returns>Value if found, default if can not found.</returns>
-    public static TValue GetOrAdd<TKey, TValue>(this ConcurrentDictionary<TKey, TValue> dictionary, TKey key, Func<TValue> factory)
+    public static TValue GetOrAdd<TKey, TValue>(this ConcurrentDictionary<TKey, TValue> dictionary, TKey key, Func<TValue> factory) where TKey : notnull
     {
         return dictionary.GetOrAdd(key, k => factory());
     }
@@ -138,7 +138,7 @@ public static class AbpDictionaryExtensions
     public static dynamic ConvertToDynamicObject(this Dictionary<string, object> dictionary)
     {
         var expandoObject = new ExpandoObject();
-        var expendObjectCollection = (ICollection<KeyValuePair<string, object>>)expandoObject;
+        var expendObjectCollection = (ICollection<KeyValuePair<string, object>>)expandoObject!;
 
         foreach (var keyValuePair in dictionary)
         {

framework/src/Volo.Abp.Core/System/Collections/Generic/AbpListExtensions.cs

@@ -196,7 +196,7 @@ public static class AbpListExtensions
     public static List<T> SortByDependencies<T>(
         this IEnumerable<T> source,
         Func<T, IEnumerable<T>> getDependencies,
-        IEqualityComparer<T> comparer = null)
+        IEqualityComparer<T>? comparer = null) where T : notnull
     {
         /* See: http://www.codeproject.com/Articles/869059/Topological-sorting-in-Csharp
          *      http://en.wikipedia.org/wiki/Topological_sorting
@@ -222,7 +222,7 @@ public static class AbpListExtensions
     /// <param name="sorted">List with the sortet items</param>
     /// <param name="visited">Dictionary with the visited items</param>
     private static void SortByDependenciesVisit<T>(T item, Func<T, IEnumerable<T>> getDependencies, List<T> sorted,
-        Dictionary<T, bool> visited)
+        Dictionary<T, bool> visited) where T : notnull
     {
         bool inProcess;
         var alreadyVisited = visited.TryGetValue(item, out inProcess);

framework/src/Volo.Abp.Core/System/Linq/PredicateOperator.cs

@@ -42,7 +42,7 @@ public static class PredicateBuilder
     }
 
     /// <summary> Start an expression </summary>
-    public static ExpressionStarter<T> New<T>(Expression<Func<T, bool>> expr = null)
+    public static ExpressionStarter<T> New<T>(Expression<Func<T, bool>>? expr = null)
     {
         return new ExpressionStarter<T>(expr);
     }
@@ -58,7 +58,7 @@ public static class PredicateBuilder
         [NotNull] Expression<Func<T, bool>> expr2)
     {
         var expr2Body = new RebindParameterVisitor(expr2.Parameters[0], expr1.Parameters[0]).Visit(expr2.Body);
-        return Expression.Lambda<Func<T, bool>>(Expression.OrElse(expr1.Body, expr2Body), expr1.Parameters);
+        return Expression.Lambda<Func<T, bool>>(Expression.OrElse(expr1.Body, expr2Body!), expr1.Parameters);
     }
 
     /// <summary> AND </summary>
@@ -66,7 +66,7 @@ public static class PredicateBuilder
         [NotNull] Expression<Func<T, bool>> expr2)
     {
         var expr2Body = new RebindParameterVisitor(expr2.Parameters[0], expr1.Parameters[0]).Visit(expr2.Body);
-        return Expression.Lambda<Func<T, bool>>(Expression.AndAlso(expr1.Body, expr2Body), expr1.Parameters);
+        return Expression.Lambda<Func<T, bool>>(Expression.AndAlso(expr1.Body, expr2Body!), expr1.Parameters);
     }
 
     /// <summary>
@@ -120,16 +120,16 @@ public class ExpressionStarter<T>
         }
     }
 
-    public ExpressionStarter(Expression<Func<T, bool>> exp) : this(false)
+    public ExpressionStarter(Expression<Func<T, bool>>? exp) : this(false)
     {
         _predicate = exp;
     }
 
     /// <summary>The actual Predicate. It can only be set by calling Start.</summary>
     private Expression<Func<T, bool>> Predicate =>
-        (IsStarted || !UseDefaultExpression) ? _predicate : DefaultExpression;
+        ((IsStarted || !UseDefaultExpression) ? _predicate : DefaultExpression)!;
 
-    private Expression<Func<T, bool>> _predicate;
+    private Expression<Func<T, bool>>? _predicate;
 
     /// <summary>Determines if the predicate is started.</summary>
     public bool IsStarted => _predicate != null;
@@ -138,7 +138,7 @@ public class ExpressionStarter<T>
     public bool UseDefaultExpression => DefaultExpression != null;
 
     /// <summary>The default expression</summary>
-    public Expression<Func<T, bool>> DefaultExpression { get; set; }
+    public Expression<Func<T, bool>>? DefaultExpression { get; set; }
 
     /// <summary>Set the Expression predicate</summary>
     /// <param name="exp">The first expression</param>
@@ -165,7 +165,7 @@ public class ExpressionStarter<T>
     }
 
     /// <summary> Show predicate string </summary>
-    public override string ToString()
+    public override string? ToString()
     {
         return Predicate?.ToString();
     }
@@ -176,7 +176,7 @@ public class ExpressionStarter<T>
     /// Allows this object to be implicitely converted to an Expression{Func{T, bool}}.
     /// </summary>
     /// <param name="right"></param>
-    public static implicit operator Expression<Func<T, bool>>(ExpressionStarter<T> right)
+    public static implicit operator Expression<Func<T, bool>>?(ExpressionStarter<T>? right)
     {
         return right?.Predicate;
     }
@@ -185,7 +185,7 @@ public class ExpressionStarter<T>
     /// Allows this object to be implicitely converted to an Expression{Func{T, bool}}.
     /// </summary>
     /// <param name="right"></param>
-    public static implicit operator Func<T, bool>(ExpressionStarter<T> right)
+    public static implicit operator Func<T, bool>?(ExpressionStarter<T>? right)
     {
         return right == null ? null :
             (right.IsStarted || right.UseDefaultExpression) ? right.Predicate.Compile() : null;
@@ -195,7 +195,7 @@ public class ExpressionStarter<T>
     /// Allows this object to be implicitely converted to an Expression{Func{T, bool}}.
     /// </summary>
     /// <param name="right"></param>
-    public static implicit operator ExpressionStarter<T>(Expression<Func<T, bool>> right)
+    public static implicit operator ExpressionStarter<T>?(Expression<Func<T, bool>>? right)
     {
         return right == null ? null : new ExpressionStarter<T>(right);
     }
@@ -240,7 +240,7 @@ public class ExpressionStarter<T>
 
 #if !(NET35)
     /// <summary></summary>
-    public string Name => Predicate.Name;
+    public string? Name => Predicate.Name;
 
     /// <summary></summary>
     public Type ReturnType => Predicate.ReturnType;

framework/src/Volo.Abp.Core/System/Reflection/AbpAssemblyExtensions.cs

@@ -6,6 +6,6 @@ public static class AbpAssemblyExtensions
 {
     public static string GetFileVersion(this Assembly assembly)
     {
-        return FileVersionInfo.GetVersionInfo(assembly.Location).FileVersion;
+        return FileVersionInfo.GetVersionInfo(assembly.Location).FileVersion!;
     }
 }

framework/src/Volo.Abp.Core/System/Reflection/AbpMemberInfoExtensions.cs

@@ -14,7 +14,7 @@ public static class AbpMemberInfoExtensions
     /// <param name="memberInfo">The member that will be checked for the attribute</param>
     /// <param name="inherit">Include inherited attributes</param>
     /// <returns>Returns the attribute object if found. Returns null if not found.</returns>
-    public static TAttribute GetSingleAttributeOrNull<TAttribute>(this MemberInfo memberInfo, bool inherit = true)
+    public static TAttribute? GetSingleAttributeOrNull<TAttribute>(this MemberInfo memberInfo, bool inherit = true)
         where TAttribute : Attribute
     {
         if (memberInfo == null)
@@ -32,7 +32,7 @@ public static class AbpMemberInfoExtensions
     }
 
 
-    public static TAttribute GetSingleAttributeOfTypeOrBaseTypesOrNull<TAttribute>(this Type type, bool inherit = true)
+    public static TAttribute? GetSingleAttributeOfTypeOrBaseTypesOrNull<TAttribute>(this Type type, bool inherit = true)
         where TAttribute : Attribute
     {
         var attr = type.GetTypeInfo().GetSingleAttributeOrNull<TAttribute>();
@@ -46,6 +46,6 @@ public static class AbpMemberInfoExtensions
             return null;
         }
 
-        return type.GetTypeInfo().BaseType.GetSingleAttributeOfTypeOrBaseTypesOrNull<TAttribute>(inherit);
+        return type.GetTypeInfo().BaseType?.GetSingleAttributeOfTypeOrBaseTypesOrNull<TAttribute>(inherit);
     }
 }

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

@@ -5,6 +5,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <AssemblyName>Volo.Abp.Core</AssemblyName>
     <PackageId>Volo.Abp.Core</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>

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

@@ -19,13 +19,13 @@ public abstract class AbpApplicationBase : IAbpApplication
     [NotNull]
     public Type StartupModuleType { get; }
 
-    public IServiceProvider ServiceProvider { get; private set; }
+    public IServiceProvider ServiceProvider { get; private set; } = default!;
 
     public IServiceCollection Services { get; }
 
     public IReadOnlyList<IAbpModuleDescriptor> Modules { get; }
 
-    public string ApplicationName { get; }
+    public string? ApplicationName { get; }
 
     public string InstanceId { get; } = Guid.NewGuid().ToString();
 
@@ -34,7 +34,7 @@ public abstract class AbpApplicationBase : IAbpApplication
     internal AbpApplicationBase(
         [NotNull] Type startupModuleType,
         [NotNull] IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction)
+        Action<AbpApplicationCreationOptions>? optionsAction)
     {
         Check.NotNull(startupModuleType, nameof(startupModuleType));
         Check.NotNull(services, nameof(services));
@@ -224,7 +224,7 @@ public abstract class AbpApplicationBase : IAbpApplication
         {
             if (module.Instance is AbpModule abpModule)
             {
-                abpModule.ServiceConfigurationContext = null;
+                abpModule.ServiceConfigurationContext = null!;
             }
         }
 
@@ -315,7 +315,7 @@ public abstract class AbpApplicationBase : IAbpApplication
         {
             if (module.Instance is AbpModule abpModule)
             {
-                abpModule.ServiceConfigurationContext = null;
+                abpModule.ServiceConfigurationContext = null!;
             }
         }
 
@@ -324,11 +324,11 @@ public abstract class AbpApplicationBase : IAbpApplication
         TryToSetEnvironment(Services);
     }
 
-    private static string GetApplicationName(AbpApplicationCreationOptions options)
+    private static string? GetApplicationName(AbpApplicationCreationOptions options)
     {
         if (!string.IsNullOrWhiteSpace(options.ApplicationName))
         {
-            return options.ApplicationName;
+            return options.ApplicationName!;
         }
 
         var configuration = options.Services.GetConfigurationOrNull();
@@ -337,7 +337,7 @@ public abstract class AbpApplicationBase : IAbpApplication
             var appNameConfig = configuration["ApplicationName"];
             if (!string.IsNullOrWhiteSpace(appNameConfig))
             {
-                return appNameConfig;
+                return appNameConfig!;
             }
         }
 

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

@@ -21,11 +21,9 @@ public class AbpApplicationCreationOptions
 
     public bool SkipConfigureServices { get; set; }
 
-    [CanBeNull]
+    public string? ApplicationName { get; set; }
-    public string ApplicationName { get; set; }
 
-    [CanBeNull]
+    public string? Environment { get; set; }
-    public string Environment { get; set; }
 
     public AbpApplicationCreationOptions([NotNull] IServiceCollection services)
     {

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

@@ -9,7 +9,7 @@ namespace Volo.Abp;
 public static class AbpApplicationFactory
 {
     public async static Task<IAbpApplicationWithInternalServiceProvider> CreateAsync<TStartupModule>(
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
         where TStartupModule : IAbpModule
     {
         var app = Create(typeof(TStartupModule), options =>
@@ -23,7 +23,7 @@ public static class AbpApplicationFactory
 
     public async static Task<IAbpApplicationWithInternalServiceProvider> CreateAsync(
         [NotNull] Type startupModuleType,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
     {
         var app = new AbpApplicationWithInternalServiceProvider(startupModuleType, options =>
         {
@@ -36,7 +36,7 @@ public static class AbpApplicationFactory
 
     public async static Task<IAbpApplicationWithExternalServiceProvider> CreateAsync<TStartupModule>(
         [NotNull] IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
         where TStartupModule : IAbpModule
     {
         var app = Create(typeof(TStartupModule), services, options =>
@@ -51,7 +51,7 @@ public static class AbpApplicationFactory
     public async static Task<IAbpApplicationWithExternalServiceProvider> CreateAsync(
         [NotNull] Type startupModuleType,
         [NotNull] IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
     {
         var app = new AbpApplicationWithExternalServiceProvider(startupModuleType, services, options =>
         {
@@ -63,7 +63,7 @@ public static class AbpApplicationFactory
     }
 
     public static IAbpApplicationWithInternalServiceProvider Create<TStartupModule>(
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
         where TStartupModule : IAbpModule
     {
         return Create(typeof(TStartupModule), optionsAction);
@@ -71,14 +71,14 @@ public static class AbpApplicationFactory
 
     public static IAbpApplicationWithInternalServiceProvider Create(
         [NotNull] Type startupModuleType,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
     {
         return new AbpApplicationWithInternalServiceProvider(startupModuleType, optionsAction);
     }
 
     public static IAbpApplicationWithExternalServiceProvider Create<TStartupModule>(
         [NotNull] IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
         where TStartupModule : IAbpModule
     {
         return Create(typeof(TStartupModule), services, optionsAction);
@@ -87,7 +87,7 @@ public static class AbpApplicationFactory
     public static IAbpApplicationWithExternalServiceProvider Create(
         [NotNull] Type startupModuleType,
         [NotNull] IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+        Action<AbpApplicationCreationOptions>? optionsAction = null)
     {
         return new AbpApplicationWithExternalServiceProvider(startupModuleType, services, optionsAction);
     }

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

@@ -10,7 +10,7 @@ internal class AbpApplicationWithExternalServiceProvider : AbpApplicationBase, I
     public AbpApplicationWithExternalServiceProvider(
         [NotNull] Type startupModuleType,
         [NotNull] IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction
+        Action<AbpApplicationCreationOptions>? optionsAction
         ) : base(
             startupModuleType,
             services,
@@ -23,6 +23,7 @@ internal class AbpApplicationWithExternalServiceProvider : AbpApplicationBase, I
     {
         Check.NotNull(serviceProvider, nameof(serviceProvider));
 
+        // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
         if (ServiceProvider != null)
         {
             if (ServiceProvider != serviceProvider)

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

@@ -7,11 +7,11 @@ namespace Volo.Abp;
 
 internal class AbpApplicationWithInternalServiceProvider : AbpApplicationBase, IAbpApplicationWithInternalServiceProvider
 {
-    public IServiceScope ServiceScope { get; private set; }
+    public IServiceScope? ServiceScope { get; private set; }
 
     public AbpApplicationWithInternalServiceProvider(
         [NotNull] Type startupModuleType,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction
+        Action<AbpApplicationCreationOptions>? optionsAction
         ) : this(
         startupModuleType,
         new ServiceCollection(),
@@ -23,7 +23,7 @@ internal class AbpApplicationWithInternalServiceProvider : AbpApplicationBase, I
     private AbpApplicationWithInternalServiceProvider(
         [NotNull] Type startupModuleType,
         [NotNull] IServiceCollection services,
-        [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction
+        Action<AbpApplicationCreationOptions>? optionsAction
         ) : base(
             startupModuleType,
             services,
@@ -34,6 +34,7 @@ internal class AbpApplicationWithInternalServiceProvider : AbpApplicationBase, I
 
     public IServiceProvider CreateServiceProvider()
     {
+        // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
         if (ServiceProvider != null)
         {
             return ServiceProvider;
@@ -42,7 +43,7 @@ internal class AbpApplicationWithInternalServiceProvider : AbpApplicationBase, I
         ServiceScope = Services.BuildServiceProviderFromFactory().CreateScope();
         SetServiceProvider(ServiceScope.ServiceProvider);
 
-        return ServiceProvider;
+        return ServiceProvider!;
     }
 
     public async Task InitializeAsync()

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

@@ -2,5 +2,5 @@
 
 public class AbpHostEnvironment : IAbpHostEnvironment
 {
-    public string EnvironmentName { get; set; }
+    public string? EnvironmentName { get; set; }
 }

framework/src/Volo.Abp.Core/Volo/Abp/Bundling/BundleContext.cs

@@ -14,7 +14,7 @@ public class BundleContext
     }
 
     public void Add(string source, bool excludeFromBundle = false,
-        Dictionary<string, string> additionalProperties = null)
+        Dictionary<string, string>? additionalProperties = null)
     {
         var bundleDefinition = new BundleDefinition
         {

framework/src/Volo.Abp.Core/Volo/Abp/Bundling/BundleDefinition.cs

@@ -4,7 +4,7 @@ namespace Volo.Abp.Bundling;
 
 public class BundleDefinition
 {
-    public string Source { get; set; }
+    public string Source { get; set; } = default!;
 
     public Dictionary<string, string> AdditionalProperties { get; set; }
 

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

@@ -13,17 +13,17 @@ public class BusinessException : Exception,
     IHasErrorDetails,
     IHasLogLevel
 {
-    public string Code { get; set; }
+    public string? Code { get; set; }
 
-    public string Details { get; set; }
+    public string? Details { get; set; }
 
     public LogLevel LogLevel { get; set; }
 
     public BusinessException(
-        string code = null,
+        string? code = null,
-        string message = null,
+        string? message = null,
-        string details = null,
+        string? details = null,
-        Exception innerException = null,
+        Exception? innerException = null,
         LogLevel logLevel = LogLevel.Warning)
         : base(message, innerException)
     {

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

@@ -136,8 +136,8 @@ public static class Check
         return type;
     }
 
-    public static string Length(
+    public static string? Length(
-        [CanBeNull] string value,
+        string? value,
         [InvokerParameterName][NotNull] string parameterName,
         int maxLength,
         int minLength = 0)
@@ -149,7 +149,7 @@ public static class Check
                 throw new ArgumentException(parameterName + " can not be null or empty!", parameterName);
             }
 
-            if (value.Length < minLength)
+            if (value!.Length < minLength)
             {
                 throw new ArgumentException($"{parameterName} length must be equal to or bigger than {minLength}!", parameterName);
             }

framework/src/Volo.Abp.Core/Volo/Abp/Content/IRemoteStreamContent.cs

@@ -5,7 +5,7 @@ namespace Volo.Abp.Content;
 
 public interface IRemoteStreamContent : IDisposable
 {
-    string FileName { get; }
+    string? FileName { get; }
 
     string ContentType { get; }
 

framework/src/Volo.Abp.Core/Volo/Abp/Content/RemoteStreamContent.cs

@@ -8,13 +8,13 @@ public class RemoteStreamContent : IRemoteStreamContent
     private readonly bool _disposeStream;
     private bool _disposed;
 
-    public virtual string FileName { get; }
+    public virtual string? FileName { get; }
 
     public virtual string ContentType { get; } = "application/octet-stream";
 
     public virtual long? ContentLength { get; }
 
-    public RemoteStreamContent(Stream stream, string fileName = null, string contentType = null, long? readOnlyLength = null, bool disposeStream = true)
+    public RemoteStreamContent(Stream stream, string? fileName = null, string? contentType = null, long? readOnlyLength = null, bool disposeStream = true)
     {
         _stream = stream;
 

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/AbpLazyServiceProvider.cs

@@ -28,12 +28,12 @@ public class AbpLazyServiceProvider :
         return this.GetRequiredService(serviceType);
     }
 
-    public virtual T LazyGetService<T>()
+    public virtual T? LazyGetService<T>()
     {
-        return (T)LazyGetService(typeof(T));
+        return (T?)LazyGetService(typeof(T));
     }
 
-    public virtual object LazyGetService(Type serviceType)
+    public virtual object? LazyGetService(Type serviceType)
     {
         return GetService(serviceType);
     }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/CachedServiceProviderBase.cs

@@ -6,26 +6,26 @@ namespace Volo.Abp.DependencyInjection;
 public abstract class CachedServiceProviderBase : ICachedServiceProviderBase
 {
     protected IServiceProvider ServiceProvider { get; }
-    protected ConcurrentDictionary<Type, Lazy<object>> CachedServices { get; }
+    protected ConcurrentDictionary<Type, Lazy<object?>> CachedServices { get; }
 
     protected CachedServiceProviderBase(IServiceProvider serviceProvider)
     {
         ServiceProvider = serviceProvider;
-        CachedServices = new ConcurrentDictionary<Type, Lazy<object>>();
+        CachedServices = new ConcurrentDictionary<Type, Lazy<object?>>();
-        CachedServices.TryAdd(typeof(IServiceProvider), new Lazy<object>(() => ServiceProvider));
+        CachedServices.TryAdd(typeof(IServiceProvider), new Lazy<object?>(() => ServiceProvider));
     }
 
-    public virtual object GetService(Type serviceType)
+    public virtual object? GetService(Type serviceType)
     {
         return CachedServices.GetOrAdd(
             serviceType,
-            _ => new Lazy<object>(() => ServiceProvider.GetService(serviceType))
+            _ => new Lazy<object?>(() => ServiceProvider.GetService(serviceType))
         ).Value;
     }
     
     public T GetService<T>(T defaultValue)
     {
-        return (T)GetService(typeof(T), defaultValue);
+        return (T)GetService(typeof(T), defaultValue!);
     }
 
     public object GetService(Type serviceType, object defaultValue)
@@ -42,7 +42,7 @@ public abstract class CachedServiceProviderBase : ICachedServiceProviderBase
     {
         return CachedServices.GetOrAdd(
             serviceType,
-            _ => new Lazy<object>(() => factory(ServiceProvider))
+            _ => new Lazy<object?>(() => factory(ServiceProvider))
-        ).Value;
+        ).Value!;
     }
 }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/ConventionalRegistrarBase.cs

@@ -52,12 +52,12 @@ public abstract class ConventionalRegistrarBase : IConventionalRegistrar
         }
     }
 
-    protected virtual DependencyAttribute GetDependencyAttributeOrNull(Type type)
+    protected virtual DependencyAttribute? GetDependencyAttributeOrNull(Type type)
     {
         return type.GetCustomAttribute<DependencyAttribute>(true);
     }
 
-    protected virtual ServiceLifetime? GetLifeTimeOrNull(Type type, [CanBeNull] DependencyAttribute dependencyAttribute)
+    protected virtual ServiceLifetime? GetLifeTimeOrNull(Type type, DependencyAttribute? dependencyAttribute)
     {
         return dependencyAttribute?.Lifetime ?? GetServiceLifetimeFromClassHierarchy(type) ?? GetDefaultLifeTimeOrNull(type);
     }
@@ -110,7 +110,7 @@ public abstract class ConventionalRegistrarBase : IConventionalRegistrar
             {
                 return ServiceDescriptor.Describe(
                     exposingServiceType,
-                    provider => provider.GetService(redirectedType),
+                    provider => provider.GetService(redirectedType)!,
                     lifeTime
                 );
             }
@@ -123,7 +123,7 @@ public abstract class ConventionalRegistrarBase : IConventionalRegistrar
         );
     }
 
-    protected virtual Type GetRedirectedTypeOrNull(
+    protected virtual Type? GetRedirectedTypeOrNull(
         Type implementationType,
         Type exposingServiceType,
         List<Type> allExposingServiceTypes)

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/IAbpLazyServiceProvider.cs

@@ -24,13 +24,13 @@ public interface IAbpLazyServiceProvider : ICachedServiceProviderBase
     /// This method is equivalent of the GetService method.
     /// It does exists for backward compatibility.
     /// </summary>
-    T LazyGetService<T>();
+    T? LazyGetService<T>();
 
     /// <summary>
     /// This method is equivalent of the GetService method.
     /// It does exists for backward compatibility.
     /// </summary>
-    object LazyGetService(Type serviceType);
+    object? LazyGetService(Type serviceType);
 
     /// <summary>
     /// This method is equivalent of the <see cref="ICachedServiceProviderBase.GetService{T}(T)"/> method.

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/IObjectAccessor.cs

@@ -4,6 +4,5 @@ namespace Volo.Abp.DependencyInjection;
 
 public interface IObjectAccessor<out T>
 {
-    [CanBeNull]
+    T? Value { get; }
-    T Value { get; }
 }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/ObjectAccessor.cs

@@ -4,14 +4,14 @@ namespace Volo.Abp.DependencyInjection;
 
 public class ObjectAccessor<T> : IObjectAccessor<T>
 {
-    public T Value { get; set; }
+    public T? Value { get; set; }
 
     public ObjectAccessor()
     {
 
     }
 
-    public ObjectAccessor([CanBeNull] T obj)
+    public ObjectAccessor(T? obj)
     {
         Value = obj;
     }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/RootServiceProvider.cs

@@ -9,10 +9,10 @@ public class RootServiceProvider : IRootServiceProvider, ISingletonDependency
     
     public RootServiceProvider(IObjectAccessor<IServiceProvider> objectAccessor)
     {
-        ServiceProvider = objectAccessor.Value;
+        ServiceProvider = objectAccessor.Value!;
     }
 
-    public virtual object GetService(Type serviceType)
+    public virtual object? GetService(Type serviceType)
     {
         return ServiceProvider.GetService(serviceType);
     }

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

@@ -37,8 +37,7 @@ public class DisposeAction<T> : IDisposable
 {
     private readonly Action<T> _action;
 
-    [CanBeNull]
+    private readonly T? _parameter;
-    private readonly T _parameter;
 
     /// <summary>
     /// Creates a new <see cref="DisposeAction"/> object.
@@ -55,6 +54,9 @@ public class DisposeAction<T> : IDisposable
 
     public void Dispose()
     {
-        _action(_parameter);
+        if (_parameter != null)
+        {
+            _action(_parameter);
+        }
     }
 }

framework/src/Volo.Abp.Core/Volo/Abp/DynamicProxy/ProxyHelper.cs

@@ -28,7 +28,7 @@ public static class ProxyHelper
             return obj;
         }
 
-        return targetField.GetValue(obj);
+        return targetField.GetValue(obj)!;
     }
 
     public static Type GetUnProxiedType(object obj)
@@ -36,15 +36,12 @@ public static class ProxyHelper
         if (obj.GetType().Namespace == ProxyNamespace)
         {
             var target = UnProxy(obj);
-            if (target != null)
+            if (target == obj)
             {
-                if (target == obj)
+                return obj.GetType().GetTypeInfo().BaseType!;
-                {
-                    return obj.GetType().GetTypeInfo().BaseType;
-                }
-
-                return target.GetType();
             }
+
+            return target.GetType();
         }
 
         return obj.GetType();

framework/src/Volo.Abp.Core/Volo/Abp/ExceptionHandling/IHasErrorCode.cs

@@ -2,5 +2,5 @@
 
 public interface IHasErrorCode
 {
-    string Code { get; }
+    string? Code { get; }
 }

framework/src/Volo.Abp.Core/Volo/Abp/ExceptionHandling/IHasErrorDetails.cs

@@ -2,5 +2,5 @@ namespace Volo.Abp.ExceptionHandling;
 
 public interface IHasErrorDetails
 {
-    string Details { get; }
+    string? Details { get; }
 }

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

@@ -2,5 +2,5 @@
 
 public interface IAbpHostEnvironment
 {
-    string EnvironmentName { get; set; }
+    string? EnvironmentName { get; set; }
 }

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

@@ -9,8 +9,7 @@ public interface IApplicationInfoAccessor
     /// This is useful for systems with multiple applications, to distinguish
     /// resources of the applications located together.
     /// </summary>
-    [CanBeNull]
+    string? ApplicationName { get; }
-    string ApplicationName { get; }
     
     /// <summary>
     /// A unique identifier for this application instance.

framework/src/Volo.Abp.Core/Volo/Abp/IO/FileHelper.cs

@@ -36,8 +36,7 @@ public static class FileHelper
     /// Returns extension without dot.
     /// Returns null if given <paramref name="fileNameWithExtension"></paramref> does not include dot.
     /// </returns>
-    [CanBeNull]
+    public static string? GetExtension([NotNull] string fileNameWithExtension)
-    public static string GetExtension([NotNull] string fileNameWithExtension)
     {
         Check.NotNull(fileNameWithExtension, nameof(fileNameWithExtension));
 
@@ -90,7 +89,7 @@ public static class FileHelper
     /// <param name="fileOptions">Indicates FileStream options. Default is Asynchronous (The file is to be used for asynchronous reading.) and SequentialScan (The file is to be accessed sequentially from beginning to end.) </param>
     /// <returns>A string containing all lines of the file.</returns>
     public static async Task<string[]> ReadAllLinesAsync(string path,
-        Encoding encoding = null,
+        Encoding? encoding = null,
         FileMode fileMode = FileMode.Open,
         FileAccess fileAccess = FileAccess.Read,
         FileShare fileShare = FileShare.Read,
@@ -114,7 +113,7 @@ public static class FileHelper
         {
             using (var reader = new StreamReader(stream, encoding))
             {
-                string line;
+                string? line;
                 while ((line = await reader.ReadLineAsync()) != null)
                 {
                     lines.Add(line);
@@ -134,6 +133,6 @@ public static class FileHelper
     {
         var content = await ReadAllBytesAsync(path);
 
-        return StringHelper.ConvertFromBytesWithoutBom(content);
+        return StringHelper.ConvertFromBytesWithoutBom(content)!;
     }
 }

framework/src/Volo.Abp.Core/Volo/Abp/Localization/CultureHelper.cs

@@ -7,7 +7,7 @@ namespace Volo.Abp.Localization;
 
 public static class CultureHelper
 {
-    public static IDisposable Use([NotNull] string culture, string uiCulture = null)
+    public static IDisposable Use([NotNull] string culture, string? uiCulture = null)
     {
         Check.NotNull(culture, nameof(culture));
 
@@ -19,7 +19,7 @@ public static class CultureHelper
         );
     }
 
-    public static IDisposable Use([NotNull] CultureInfo culture, CultureInfo uiCulture = null)
+    public static IDisposable Use([NotNull] CultureInfo culture, CultureInfo? uiCulture = null)
     {
         Check.NotNull(culture, nameof(culture));
 

framework/src/Volo.Abp.Core/Volo/Abp/Logging/AbpInitLogEntry.cs

@@ -9,11 +9,11 @@ public class AbpInitLogEntry
 
     public EventId EventId { get; set; }
 
-    public object State { get; set; }
+    public object State { get; set; } = default!;
 
-    public Exception Exception { get; set; }
+    public Exception? Exception { get; set; }
 
-    public Func<object, Exception, string> Formatter { get; set; }
+    public Func<object, Exception?, string> Formatter { get; set; } = default!;
 
     public string Message => Formatter(State, Exception);
 }

framework/src/Volo.Abp.Core/Volo/Abp/Logging/DefaultInitLogger.cs

@@ -13,13 +13,13 @@ public class DefaultInitLogger<T> : IInitLogger<T>
         Entries = new List<AbpInitLogEntry>();
     }
 
-    public virtual void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
+    public virtual void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
     {
         Entries.Add(new AbpInitLogEntry
         {
             LogLevel = logLevel,
             EventId = eventId,
-            State = state,
+            State = state!,
             Exception = exception,
             Formatter = (s, e) => formatter((TState)s, e),
         });
@@ -30,7 +30,7 @@ public class DefaultInitLogger<T> : IInitLogger<T>
         return logLevel != LogLevel.None;
     }
 
-    public virtual IDisposable BeginScope<TState>(TState state)
+    public virtual IDisposable BeginScope<TState>(TState state) where TState : notnull
     {
         return NullDisposable.Instance;
     }

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

@@ -29,7 +29,7 @@ public abstract class AbpModule :
         internal set => _serviceConfigurationContext = value;
     }
 
-    private ServiceConfigurationContext _serviceConfigurationContext;
+    private ServiceConfigurationContext? _serviceConfigurationContext;
 
     public virtual Task PreConfigureServicesAsync(ServiceConfigurationContext context)
     {

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

@@ -12,7 +12,7 @@ public class DependsOnAttribute : Attribute, IDependedTypesProvider
     [NotNull]
     public Type[] DependedTypes { get; }
 
-    public DependsOnAttribute(params Type[] dependedTypes)
+    public DependsOnAttribute(params Type[]? dependedTypes)
     {
         DependedTypes = dependedTypes ?? new Type[0];
     }

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

@@ -85,7 +85,7 @@ public class ModuleLoader : IModuleLoader
 
     protected virtual IAbpModule CreateAndRegisterModule(IServiceCollection services, Type moduleType)
     {
-        var module = (IAbpModule)Activator.CreateInstance(moduleType);
+        var module = (IAbpModule)Activator.CreateInstance(moduleType)!;
         services.AddSingleton(moduleType, module);
         return module;
     }

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/PlugIns/FilePlugInSource.cs

@@ -8,7 +8,7 @@ public class FilePlugInSource : IPlugInSource
 {
     public string[] FilePaths { get; }
 
-    public FilePlugInSource(params string[] filePaths)
+    public FilePlugInSource(params string[]? filePaths)
     {
         FilePaths = filePaths ?? new string[0];
     }

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/PlugIns/FolderPlugInSource.cs

@@ -15,7 +15,7 @@ public class FolderPlugInSource : IPlugInSource
 
     public SearchOption SearchOption { get; set; }
 
-    public Func<string, bool> Filter { get; set; }
+    public Func<string, bool>? Filter { get; set; }
 
     public FolderPlugInSource(
         [NotNull] string folder,

framework/src/Volo.Abp.Core/Volo/Abp/Modularity/PlugIns/TypePlugInSource.cs

@@ -7,7 +7,7 @@ public class TypePlugInSource : IPlugInSource
 {
     private readonly Type[] _moduleTypes;
 
-    public TypePlugInSource(params Type[] moduleTypes)
+    public TypePlugInSource(params Type[]? moduleTypes)
     {
         _moduleTypes = moduleTypes ?? new Type[0];
     }

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

@@ -8,7 +8,7 @@ public class ServiceConfigurationContext
 {
     public IServiceCollection Services { get; }
 
-    public IDictionary<string, object> Items { get; }
+    public IDictionary<string, object?> Items { get; }
 
     /// <summary>
     /// Gets/sets arbitrary named objects those can be stored during
@@ -19,7 +19,7 @@ public class ServiceConfigurationContext
     /// </summary>
     /// <param name="key"></param>
     /// <returns></returns>
-    public object this[string key] {
+    public object? this[string key] {
         get => Items.GetOrDefault(key);
         set => Items[key] = value;
     }
@@ -27,6 +27,6 @@ public class ServiceConfigurationContext
     public ServiceConfigurationContext([NotNull] IServiceCollection services)
     {
         Services = Check.NotNull(services, nameof(services));
-        Items = new Dictionary<string, object>();
+        Items = new Dictionary<string, object?>();
     }
 }

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

@@ -29,12 +29,12 @@ public class NameValue<T>
     /// <summary>
     /// Name.
     /// </summary>
-    public string Name { get; set; }
+    public string Name { get; set; } = default!;
 
     /// <summary>
     /// Value.
     /// </summary>
-    public T Value { get; set; }
+    public T Value { get; set; } = default!;
 
     public NameValue()
     {

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

@@ -9,8 +9,8 @@ namespace Volo.Abp;
 
 public static class ObjectHelper
 {
-    private static readonly ConcurrentDictionary<string, PropertyInfo> CachedObjectProperties =
+    private static readonly ConcurrentDictionary<string, PropertyInfo?> CachedObjectProperties =
-        new ConcurrentDictionary<string, PropertyInfo>();
+        new ConcurrentDictionary<string, PropertyInfo?>();
 
     public static void TrySetProperty<TObject, TValue>(
         TObject obj,
@@ -25,9 +25,9 @@ public static class ObjectHelper
         TObject obj,
         Expression<Func<TObject, TValue>> propertySelector,
         Func<TObject, TValue> valueFactory,
-        params Type[] ignoreAttributeTypes)
+        params Type[]? ignoreAttributeTypes)
     {
-        var cacheKey = $"{obj.GetType().FullName}-" +
+        var cacheKey = $"{obj?.GetType().FullName}-" +
                        $"{propertySelector}-" +
                        $"{(ignoreAttributeTypes != null ? "-" + string.Join("-", ignoreAttributeTypes.Select(x => x.FullName)) : "")}";
 
@@ -40,7 +40,7 @@ public static class ObjectHelper
 
             var memberExpression = propertySelector.Body.As<MemberExpression>();
 
-            var propertyInfo = obj.GetType().GetProperties().FirstOrDefault(x =>
+            var propertyInfo = obj?.GetType().GetProperties().FirstOrDefault(x =>
                 x.Name == memberExpression.Member.Name &&
                 x.GetSetMethod(true) != null);
 

framework/src/Volo.Abp.Core/Volo/Abp/Options/AbpOptionsFactory.cs

@@ -9,7 +9,7 @@ public class AbpOptionsFactory<TOptions> : IOptionsFactory<TOptions> where TOpti
 {
     private readonly IEnumerable<IConfigureOptions<TOptions>> _setups;
     private readonly IEnumerable<IPostConfigureOptions<TOptions>> _postConfigures;
-    private readonly IEnumerable<IValidateOptions<TOptions>> _validations;
+    private readonly IEnumerable<IValidateOptions<TOptions>>? _validations;
 
     public AbpOptionsFactory(
         IEnumerable<IConfigureOptions<TOptions>> setups,
@@ -22,7 +22,7 @@ public class AbpOptionsFactory<TOptions> : IOptionsFactory<TOptions> where TOpti
     public AbpOptionsFactory(
         IEnumerable<IConfigureOptions<TOptions>> setups,
         IEnumerable<IPostConfigureOptions<TOptions>> postConfigures,
-        IEnumerable<IValidateOptions<TOptions>> validations)
+        IEnumerable<IValidateOptions<TOptions>>? validations)
     {
         _setups = setups;
         _postConfigures = postConfigures;

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

@@ -31,7 +31,7 @@ internal static class AssemblyHelper
         }
         catch (ReflectionTypeLoadException ex)
         {
-            return ex.Types;
+            return ex.Types!;
         }
     }
 }

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

@@ -80,7 +80,7 @@ public static class ReflectionHelper
     /// <param name="memberInfo">MemberInfo</param>
     /// <param name="defaultValue">Default value (null as default)</param>
     /// <param name="inherit">Inherit attribute from base classes</param>
-    public static TAttribute GetSingleAttributeOrDefault<TAttribute>(MemberInfo memberInfo, TAttribute defaultValue = default, bool inherit = true)
+    public static TAttribute? GetSingleAttributeOrDefault<TAttribute>(MemberInfo memberInfo, TAttribute? defaultValue = default, bool inherit = true)
         where TAttribute : Attribute
     {
         //Get attribute on the member
@@ -100,7 +100,7 @@ public static class ReflectionHelper
     /// <param name="memberInfo">MemberInfo</param>
     /// <param name="defaultValue">Default value (null as default)</param>
     /// <param name="inherit">Inherit attribute from base classes</param>
-    public static TAttribute GetSingleAttributeOfMemberOrDeclaringTypeOrDefault<TAttribute>(MemberInfo memberInfo, TAttribute defaultValue = default, bool inherit = true)
+    public static TAttribute? GetSingleAttributeOfMemberOrDeclaringTypeOrDefault<TAttribute>(MemberInfo memberInfo, TAttribute? defaultValue = default, bool inherit = true)
         where TAttribute : class
     {
         return memberInfo.GetCustomAttributes(true).OfType<TAttribute>().FirstOrDefault()
@@ -128,7 +128,7 @@ public static class ReflectionHelper
     /// <summary>
     /// Gets value of a property by it's full path from given object
     /// </summary>
-    public static object GetValueByPath(object obj, Type objectType, string propertyPath)
+    public static object? GetValueByPath(object obj, Type objectType, string propertyPath)
     {
         var value = obj;
         var currentType = objectType;
@@ -167,7 +167,7 @@ public static class ReflectionHelper
     {
         var currentType = objectType;
         PropertyInfo property;
-        var objectPath = currentType.FullName;
+        var objectPath = currentType.FullName!;
         var absolutePropertyPath = propertyPath;
         if (absolutePropertyPath.StartsWith(objectPath))
         {
@@ -178,19 +178,19 @@ public static class ReflectionHelper
 
         if (properties.Length == 1)
         {
-            property = objectType.GetProperty(properties.First());
+            property = objectType.GetProperty(properties.First())!;
             property.SetValue(obj, value);
             return;
         }
 
         for (int i = 0; i < properties.Length - 1; i++)
         {
-            property = currentType.GetProperty(properties[i]);
+            property = currentType.GetProperty(properties[i])!;
-            obj = property.GetValue(obj, null);
+            obj = property.GetValue(obj, null)!;
             currentType = property.PropertyType;
         }
 
-        property = currentType.GetProperty(properties.Last());
+        property = currentType.GetProperty(properties.Last())!;
         property.SetValue(obj, value);
     }
 
@@ -215,7 +215,7 @@ public static class ReflectionHelper
 
             constants.AddRange(targetType.GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy)
                 .Where(x => x.IsLiteral && !x.IsInitOnly)
-                .Select(x => x.GetValue(null).ToString()));
+                .Select(x => x.GetValue(null)!.ToString()!));
 
             var nestedTypes = targetType.GetNestedTypes(BindingFlags.Public);
 

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

@@ -43,7 +43,7 @@ public static class TypeHelper
         return NonNullablePrimitiveTypes.Contains(type);
     }
 
-    public static bool IsFunc(object obj)
+    public static bool IsFunc(object? obj)
     {
         if (obj == null)
         {
@@ -59,7 +59,7 @@ public static class TypeHelper
         return type.GetGenericTypeDefinition() == typeof(Func<>);
     }
 
-    public static bool IsFunc<TReturn>(object obj)
+    public static bool IsFunc<TReturn>(object? obj)
     {
         return obj != null && obj.GetType() == typeof(Func<TReturn>);
     }
@@ -88,13 +88,13 @@ public static class TypeHelper
     {
         if (t.GetGenericArguments().Length > 0 && t.GetGenericTypeDefinition() == typeof(Nullable<>))
         {
-            return t.GetGenericArguments().FirstOrDefault();
+            return t.GetGenericArguments().First();
         }
 
         return t;
     }
 
-    public static bool IsEnumerable(Type type, out Type itemType, bool includePrimitives = true)
+    public static bool IsEnumerable(Type type, out Type? itemType, bool includePrimitives = true)
     {
         if (!includePrimitives && IsPrimitiveExtended(type))
         {
@@ -119,7 +119,7 @@ public static class TypeHelper
         return false;
     }
 
-    public static bool IsDictionary(Type type, out Type keyType, out Type valueType)
+    public static bool IsDictionary(Type type, out Type? keyType, out Type? valueType)
     {
         var dictionaryTypes = ReflectionHelper
             .GetImplementedGenericTypes(
@@ -167,12 +167,12 @@ public static class TypeHelper
                type == typeof(Guid);
     }
 
-    public static T GetDefaultValue<T>()
+    public static T? GetDefaultValue<T>()
     {
         return default;
     }
 
-    public static object GetDefaultValue(Type type)
+    public static object? GetDefaultValue(Type type)
     {
         if (type.IsValueType)
         {
@@ -194,7 +194,8 @@ public static class TypeHelper
         if (type.IsGenericType)
         {
             var genericType = type.GetGenericTypeDefinition();
-            return $"{genericType.FullName.Left(genericType.FullName.IndexOf('`'))}<{type.GenericTypeArguments.Select(GetFullNameHandlingNullableAndGenerics).JoinAsString(",")}>";
+            var genericTypeFullName = genericType.FullName!;
+            return $"{genericTypeFullName.Left(genericTypeFullName.IndexOf('`'))}<{type.GenericTypeArguments.Select(GetFullNameHandlingNullableAndGenerics).JoinAsString(",")}>";
         }
 
         return type.FullName ?? type.Name;
@@ -212,7 +213,8 @@ public static class TypeHelper
         if (type.IsGenericType)
         {
             var genericType = type.GetGenericTypeDefinition();
-            return $"{genericType.FullName.Left(genericType.FullName.IndexOf('`'))}<{type.GenericTypeArguments.Select(GetSimplifiedName).JoinAsString(",")}>";
+            var genericTypeFullName = genericType.FullName!;
+            return $"{genericTypeFullName.Left(genericTypeFullName.IndexOf('`'))}<{type.GenericTypeArguments.Select(GetSimplifiedName).JoinAsString(",")}>";
         }
 
         if (type == typeof(string))
@@ -303,12 +305,12 @@ public static class TypeHelper
         return type.FullName ?? type.Name;
     }
 
-    public static object ConvertFromString<TTargetType>(string value)
+    public static object? ConvertFromString<TTargetType>(string value)
     {
         return ConvertFromString(typeof(TTargetType), value);
     }
 
-    public static object ConvertFromString(Type targetType, string value)
+    public static object? ConvertFromString(Type targetType, string? value)
     {
         if (value == null)
         {
@@ -354,7 +356,7 @@ public static class TypeHelper
     {
         return TypeDescriptor
             .GetConverter(targetType)
-            .ConvertFrom(value);
+            .ConvertFrom(value)!;
     }
 
     public static Type StripNullable(Type type)
@@ -364,7 +366,7 @@ public static class TypeHelper
             : type;
     }
 
-    public static bool IsDefaultValue([CanBeNull] object obj)
+    public static bool IsDefaultValue(object? obj)
     {
         if (obj == null)
         {

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

@@ -22,7 +22,7 @@ public class RemoteServiceAttribute : Attribute //TODO: Can we move this to anot
     /// Group names of all services of a module expected to be the same.
     /// This name is also used to distinguish the service endpoint of this group.
     /// </summary>
-    public string Name { get; set; }
+    public string Name { get; set; } = default!;
 
     public RemoteServiceAttribute(bool isEnabled = true)
     {

framework/src/Volo.Abp.Core/Volo/Abp/SimpleStateChecking/ISimpleStateCheckerSerializer.cs

@@ -4,9 +4,9 @@ namespace Volo.Abp.SimpleStateChecking;
 
 public interface ISimpleStateCheckerSerializer
 {
-    public string Serialize<TState>(ISimpleStateChecker<TState> checker)
+    public string? Serialize<TState>(ISimpleStateChecker<TState> checker)
         where TState : IHasSimpleStateCheckers<TState>;
 
-    public ISimpleStateChecker<TState> Deserialize<TState>(JsonObject jsonObject, TState state)
+    public ISimpleStateChecker<TState>? Deserialize<TState>(JsonObject jsonObject, TState state)
         where TState : IHasSimpleStateCheckers<TState>;
 }

framework/src/Volo.Abp.Core/Volo/Abp/SimpleStateChecking/ISimpleStateCheckerSerializerContributor.cs

@@ -5,11 +5,9 @@ namespace Volo.Abp.SimpleStateChecking;
 
 public interface ISimpleStateCheckerSerializerContributor
 {
-    [CanBeNull]
+    public string? SerializeToJson<TState>(ISimpleStateChecker<TState> checker)
-    public string SerializeToJson<TState>(ISimpleStateChecker<TState> checker)
         where TState : IHasSimpleStateCheckers<TState>;
 
-    [CanBeNull]
+    public ISimpleStateChecker<TState>? Deserialize<TState>(JsonObject jsonObject, TState state)
-    public ISimpleStateChecker<TState> Deserialize<TState>(JsonObject jsonObject, TState state)
         where TState : IHasSimpleStateCheckers<TState>;
 }

framework/src/Volo.Abp.Core/Volo/Abp/SimpleStateChecking/SimpleStateCheckerSerializer.cs

@@ -16,8 +16,7 @@ public class SimpleStateCheckerSerializer :
         _contributors = contributors;
     }
     
-    [CanBeNull]
+    public string? Serialize<TState>(ISimpleStateChecker<TState> checker) 
-    public string Serialize<TState>(ISimpleStateChecker<TState> checker) 
         where TState : IHasSimpleStateCheckers<TState>
     {
         foreach (var contributor in _contributors)
@@ -32,8 +31,7 @@ public class SimpleStateCheckerSerializer :
         return null;
     }
 
-    [CanBeNull]
+    public ISimpleStateChecker<TState>? Deserialize<TState>(JsonObject jsonObject, TState state)
-    public ISimpleStateChecker<TState> Deserialize<TState>(JsonObject jsonObject, TState state)
         where TState : IHasSimpleStateCheckers<TState>
     {
         foreach (var contributor in _contributors)

framework/src/Volo.Abp.Core/Volo/Abp/SimpleStateChecking/SimpleStateCheckerSerializerExtensions.cs

@@ -7,7 +7,7 @@ namespace Volo.Abp.SimpleStateChecking;
 
 public static class SimpleStateCheckerSerializerExtensions
 {
-    public static string Serialize<TState>(
+    public static string? Serialize<TState>(
         this ISimpleStateCheckerSerializer serializer, 
         IList<ISimpleStateChecker<TState>> stateCheckers)
         where TState : IHasSimpleStateCheckers<TState>
@@ -73,7 +73,7 @@ public static class SimpleStateCheckerSerializerExtensions
             return new[] { checker };
         }
 
-        var checkers = new List<ISimpleStateChecker<TState>>();
+        var checkers = new List<ISimpleStateChecker<TState>?>();
 
         for (var i = 0; i < array.Count; i++)
         {
@@ -85,6 +85,6 @@ public static class SimpleStateCheckerSerializerExtensions
             checkers.Add(serializer.Deserialize(jsonObject, state));
         }
 
-        return checkers.Where(x => x != null).ToArray();
+        return checkers.Where(x => x != null).ToArray()!;
     }
 }

framework/src/Volo.Abp.Core/Volo/Abp/Text/Formatting/FormattedStringValueExtracter.cs

@@ -68,7 +68,7 @@ public class FormattedStringValueExtracter
 
                     Debug.Assert(previousToken != null, "previousToken can not be null since i > 0 here");
 
-                    result.Matches.Add(new NameValue(previousToken.Text, str.Substring(0, matchIndex)));
+                    result.Matches.Add(new NameValue(previousToken!.Text, str.Substring(0, matchIndex)));
                     str = str.Substring(matchIndex + currentToken.Text.Length);
                 }
             }

framework/src/Volo.Abp.Core/Volo/Abp/Text/StringHelper.cs

@@ -10,7 +10,7 @@ public class StringHelper
     /// <param name="bytes">The byte[] to be converted to string</param>
     /// <param name="encoding">The encoding to get string. Default is UTF8</param>
     /// <returns></returns>
-    public static string ConvertFromBytesWithoutBom(byte[] bytes, Encoding encoding = null)
+    public static string? ConvertFromBytesWithoutBom(byte[]? bytes, Encoding? encoding = null)
     {
         if (bytes == null)
         {

framework/src/Volo.Abp.Core/Volo/Abp/Threading/InternalAsyncHelper.cs

@@ -9,9 +9,9 @@ namespace Volo.Abp.Threading;
 //TODO: Cache GetMethod reflection!
 public static class InternalAsyncHelper
 {
-    public static async Task AwaitTaskWithFinally(Task actualReturnValue, Action<Exception> finalAction)
+    public static async Task AwaitTaskWithFinally(Task actualReturnValue, Action<Exception?> finalAction)
     {
-        Exception exception = null;
+        Exception? exception = null;
 
         try
         {
@@ -28,9 +28,9 @@ public static class InternalAsyncHelper
         }
     }
 
-    public static async Task AwaitTaskWithPostActionAndFinally(Task actualReturnValue, Func<Task> postAction, Action<Exception> finalAction)
+    public static async Task AwaitTaskWithPostActionAndFinally(Task actualReturnValue, Func<Task> postAction, Action<Exception?> finalAction)
     {
-        Exception exception = null;
+        Exception? exception = null;
 
         try
         {
@@ -48,9 +48,9 @@ public static class InternalAsyncHelper
         }
     }
 
-    public static async Task AwaitTaskWithPreActionAndPostActionAndFinally(Func<Task> actualReturnValue, Func<Task> preAction = null, Func<Task> postAction = null, Action<Exception> finalAction = null)
+    public static async Task AwaitTaskWithPreActionAndPostActionAndFinally(Func<Task> actualReturnValue, Func<Task>? preAction = null, Func<Task>? postAction = null, Action<Exception?>? finalAction = null)
     {
-        Exception exception = null;
+        Exception? exception = null;
 
         try
         {
@@ -80,9 +80,9 @@ public static class InternalAsyncHelper
         }
     }
 
-    public static async Task<T> AwaitTaskWithFinallyAndGetResult<T>(Task<T> actualReturnValue, Action<Exception> finalAction)
+    public static async Task<T> AwaitTaskWithFinallyAndGetResult<T>(Task<T> actualReturnValue, Action<Exception?> finalAction)
     {
-        Exception exception = null;
+        Exception? exception = null;
 
         try
         {
@@ -103,14 +103,14 @@ public static class InternalAsyncHelper
     {
         return typeof(InternalAsyncHelper)
             .GetTypeInfo()
-            .GetMethod("AwaitTaskWithFinallyAndGetResult", BindingFlags.Public | BindingFlags.Static)
+            .GetMethod("AwaitTaskWithFinallyAndGetResult", BindingFlags.Public | BindingFlags.Static)!
             .MakeGenericMethod(taskReturnType)
-            .Invoke(null, new object[] { actualReturnValue, finalAction });
+            .Invoke(null, new object[] { actualReturnValue, finalAction })!;
     }
 
-    public static async Task<T> AwaitTaskWithPostActionAndFinallyAndGetResult<T>(Task<T> actualReturnValue, Func<Task> postAction, Action<Exception> finalAction)
+    public static async Task<T> AwaitTaskWithPostActionAndFinallyAndGetResult<T>(Task<T> actualReturnValue, Func<Task> postAction, Action<Exception?> finalAction)
     {
-        Exception exception = null;
+        Exception? exception = null;
 
         try
         {
@@ -133,14 +133,14 @@ public static class InternalAsyncHelper
     {
         return typeof(InternalAsyncHelper)
             .GetTypeInfo()
-            .GetMethod("AwaitTaskWithPostActionAndFinallyAndGetResult", BindingFlags.Public | BindingFlags.Static)
+            .GetMethod("AwaitTaskWithPostActionAndFinallyAndGetResult", BindingFlags.Public | BindingFlags.Static)!
             .MakeGenericMethod(taskReturnType)
-            .Invoke(null, new object[] { actualReturnValue, action, finalAction });
+            .Invoke(null, new object[] { actualReturnValue, action, finalAction })!;
     }
 
-    public static async Task<T> AwaitTaskWithPreActionAndPostActionAndFinallyAndGetResult<T>(Func<Task<T>> actualReturnValue, Func<Task> preAction = null, Func<Task> postAction = null, Action<Exception> finalAction = null)
+    public static async Task<T> AwaitTaskWithPreActionAndPostActionAndFinallyAndGetResult<T>(Func<Task<T>> actualReturnValue, Func<Task>? preAction = null, Func<Task>? postAction = null, Action<Exception?>? finalAction = null)
     {
-        Exception exception = null;
+        Exception? exception = null;
 
         try
         {
@@ -169,19 +169,19 @@ public static class InternalAsyncHelper
         }
     }
 
-    public static object CallAwaitTaskWithPreActionAndPostActionAndFinallyAndGetResult(Type taskReturnType, Func<object> actualReturnValue, Func<Task> preAction = null, Func<Task> postAction = null, Action<Exception> finalAction = null)
+    public static object CallAwaitTaskWithPreActionAndPostActionAndFinallyAndGetResult(Type taskReturnType, Func<object> actualReturnValue, Func<Task>? preAction = null, Func<Task>? postAction = null, Action<Exception>? finalAction = null)
     {
         var returnFunc = typeof(InternalAsyncHelper)
             .GetTypeInfo()
-            .GetMethod("ConvertFuncOfObjectToFuncOfTask", BindingFlags.NonPublic | BindingFlags.Static)
+            .GetMethod("ConvertFuncOfObjectToFuncOfTask", BindingFlags.NonPublic | BindingFlags.Static)!
             .MakeGenericMethod(taskReturnType)
             .Invoke(null, new object[] { actualReturnValue });
 
         return typeof(InternalAsyncHelper)
             .GetTypeInfo()
-            .GetMethod("AwaitTaskWithPreActionAndPostActionAndFinallyAndGetResult", BindingFlags.Public | BindingFlags.Static)
+            .GetMethod("AwaitTaskWithPreActionAndPostActionAndFinallyAndGetResult", BindingFlags.Public | BindingFlags.Static)!
             .MakeGenericMethod(taskReturnType)
-            .Invoke(null, new object[] { returnFunc, preAction, postAction, finalAction });
+            .Invoke(null, new object?[] { returnFunc, preAction, postAction, finalAction })!;
     }
 
     [UsedImplicitly]

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

@@ -12,9 +12,9 @@ public class UserFriendlyException : BusinessException, IUserFriendlyException
 {
     public UserFriendlyException(
         string message,
-        string code = null,
+        string? code = null,
-        string details = null,
+        string? details = null,
-        Exception innerException = null,
+        Exception? innerException = null,
         LogLevel logLevel = LogLevel.Warning)
         : base(
               code,

framework/src/Volo.Abp.Core/Volo/Abp/Validation/DynamicMaxLengthAttribute.cs

@@ -8,7 +8,7 @@ namespace Volo.Abp.Validation;
 
 public class DynamicMaxLengthAttribute : MaxLengthAttribute
 {
-    private static readonly FieldInfo MaximumLengthField;
+    private static readonly FieldInfo? MaximumLengthField;
 
     static DynamicMaxLengthAttribute()
     {
@@ -21,7 +21,7 @@ public class DynamicMaxLengthAttribute : MaxLengthAttribute
 
     public DynamicMaxLengthAttribute(
         [NotNull] Type sourceType,
-        [CanBeNull] string maximumLengthPropertyName)
+        string? maximumLengthPropertyName)
     {
         Check.NotNull(sourceType, nameof(sourceType));
 
@@ -32,7 +32,7 @@ public class DynamicMaxLengthAttribute : MaxLengthAttribute
                 BindingFlags.Static | BindingFlags.Public
             );
             Debug.Assert(maximumLengthProperty != null, nameof(maximumLengthProperty) + " != null");
-            MaximumLengthField.SetValue(this, (int)maximumLengthProperty.GetValue(null));
+            MaximumLengthField?.SetValue(this, (int)maximumLengthProperty?.GetValue(null)!);
         }
     }
 }

framework/src/Volo.Abp.Core/Volo/Abp/Validation/DynamicRangeAttribute.cs

@@ -8,8 +8,8 @@ namespace Volo.Abp.Validation;
 
 public class DynamicRangeAttribute : RangeAttribute
 {
-    private static readonly FieldInfo MaximumField;
+    private static readonly FieldInfo? MaximumField;
-    private static readonly FieldInfo MinimumField;
+    private static readonly FieldInfo? MinimumField;
 
     static DynamicRangeAttribute()
     {
@@ -33,8 +33,8 @@ public class DynamicRangeAttribute : RangeAttribute
     public DynamicRangeAttribute(
         [NotNull] Type sourceType,
         [NotNull] Type operandType,
-        [CanBeNull] string minimumPropertyName,
+        string? minimumPropertyName,
-        [CanBeNull] string maximumPropertyName
+        string? maximumPropertyName
     )
         : base(operandType, string.Empty, string.Empty)
     {
@@ -47,7 +47,7 @@ public class DynamicRangeAttribute : RangeAttribute
                 BindingFlags.Static | BindingFlags.Public
             );
             Debug.Assert(minimumProperty != null, nameof(minimumProperty) + " != null");
-            MinimumField.SetValue(this, minimumProperty.GetValue(null));
+            MinimumField?.SetValue(this, minimumProperty?.GetValue(null));
         }
 
         if (maximumPropertyName != null)
@@ -57,7 +57,7 @@ public class DynamicRangeAttribute : RangeAttribute
                 BindingFlags.Static | BindingFlags.Public
             );
             Debug.Assert(maximumProperty != null, nameof(maximumProperty) + " != null");
-            MaximumField.SetValue(this, maximumProperty.GetValue(null));
+            MaximumField?.SetValue(this, maximumProperty?.GetValue(null));
         }
     }
 }

framework/src/Volo.Abp.Core/Volo/Abp/Validation/DynamicStringLengthAttribute.cs

@@ -12,7 +12,7 @@ namespace Volo.Abp.Validation;
 /// </summary>
 public class DynamicStringLengthAttribute : StringLengthAttribute
 {
-    private static readonly FieldInfo MaximumLengthField;
+    private static readonly FieldInfo? MaximumLengthField;
 
     static DynamicStringLengthAttribute()
     {
@@ -28,8 +28,8 @@ public class DynamicStringLengthAttribute : StringLengthAttribute
     /// <param name="minimumLengthPropertyName">The name of the public static property for the <see cref="StringLengthAttribute.MinimumLength"/></param>
     public DynamicStringLengthAttribute(
         [NotNull] Type sourceType,
-        [CanBeNull] string maximumLengthPropertyName,
+        string? maximumLengthPropertyName,
-        [CanBeNull] string minimumLengthPropertyName = null)
+        string? minimumLengthPropertyName = null)
         : base(0)
     {
         Check.NotNull(sourceType, nameof(sourceType));
@@ -41,7 +41,7 @@ public class DynamicStringLengthAttribute : StringLengthAttribute
                 BindingFlags.Static | BindingFlags.Public
             );
             Debug.Assert(maximumLengthProperty != null, nameof(maximumLengthProperty) + " != null");
-            MaximumLengthField.SetValue(this, (int)maximumLengthProperty.GetValue(null));
+            MaximumLengthField?.SetValue(this, (int)maximumLengthProperty?.GetValue(null)!);
         }
 
         if (minimumLengthPropertyName != null)
@@ -51,7 +51,7 @@ public class DynamicStringLengthAttribute : StringLengthAttribute
                 BindingFlags.Static | BindingFlags.Public
             );
             Debug.Assert(minimumLengthProperty != null, nameof(minimumLengthProperty) + " != null");
-            MinimumLength = (int)minimumLengthProperty.GetValue(null);
+            MinimumLength = (int)minimumLengthProperty?.GetValue(null)!;
         }
     }
 }