[DataContract]
    public class Book
    {
        [DataMember]
        public int Code { get; set; }

        [DataMember]
        public string Title { get; set; }

        [DataMember]
        public string Author { get; set; }
    }

   [ServiceContract]
    public interface IBookService
    {
        [OperationContract( AsyncPattern = true )]
        IAsyncResult BeginGetAllBook( AsyncCallback callback, object state );

        IEnumerable<Book> EndGetAllBook( IAsyncResult asyncResult ); 
    }

[OperationContract]
IEnumerable<Book> GetAllBook(int code , AsyncCallback callback, object state );

 public class CompletedAsyncResult<TEntity> : IAsyncResult where TEntity : class , new()
    {
        public IList<TEntity> Result
        {
            get
            {
                return _result;
            }
            set
            {
                _result = value;
            }
        }
        private IList<TEntity> _result;

        public CompletedAsyncResult( IList<TEntity> data )
        {
            this.Result = data;
        }

        public object AsyncState
        {
            get
            {
                return ( IList<TEntity> )Result;
            }
        }

        public WaitHandle AsyncWaitHandle
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public bool CompletedSynchronously
        {
            get
            {
                return true;
            }
        }

        public bool IsCompleted
        {
            get
            {
                return true;
            }
        }
    }

 public class BookService : IBookService
    {
        public BookService()
        {
            ListOfBook = new List<Book>();
        }

        public List<Book> ListOfBook
        {
            get;
            private set;
        }

        private List<Book> CreateListOfBook()
        {
            Parallel.For( 0, 10000, ( int counter ) =>
            {
                ListOfBook.Add( new Book()
                {
                    Code = counter,
                    Title = String.Format( "Book {0}", counter ),
                    Author = "Masoud Pakdel"
                } );
            } );

            return ListOfBook;
        }

        public IAsyncResult BeginGetAllBook( AsyncCallback callback, object state )
        {
            var result = CreateListOfBook();
            return new CompletedAsyncResult<Book>( result );
        }

        public IEnumerable<Book> EndGetAllBook( IAsyncResult asyncResult )
        {
            return ( ( CompletedAsyncResult<Book> )asyncResult ).Result;
        }
    }

[System.Diagnostics.DebuggerStepThroughAttribute()]
    [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")]
    public partial class BookServiceClient : System.ServiceModel.ClientBase<UI.BookService.IBookService>, UI.BookService.IBookService {
        
        public BookServiceClient() {
        }
        
        public BookServiceClient(string endpointConfigurationName) : 
                base(endpointConfigurationName) {
        }
        
        public BookServiceClient(string endpointConfigurationName, string remoteAddress) : 
                base(endpointConfigurationName, remoteAddress) {
        }
        
        public BookServiceClient(string endpointConfigurationName, System.ServiceModel.EndpointAddress remoteAddress) : 
                base(endpointConfigurationName, remoteAddress) {
        }
        
        public BookServiceClient(System.ServiceModel.Channels.Binding binding, System.ServiceModel.EndpointAddress remoteAddress) : 
                base(binding, remoteAddress) {
        }
        
        public UI.BookService.Book[] BeginGetAllBook() {
            return base.Channel.BeginGetAllBook();
        }
    }

System.ServiceModel.ClientBase<UI.BookService.IBookService>

 Could not load file or assembly Newtonsoft.Json or one of its dependencies. The system cannot find the file specified.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <!-- ... -->
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

 PM> Get-Project -All | Add-BindingRedirect

• دریافت KB2468871

• ریز جزئیات KB2468871

public class Article1
{
    public string Title { get; set; }
    public string? Subtitle { get; set; }
    public string Author { get; set; }
    public DateTime Published { get; set; }
}

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
</Project>

Non-nullable property 'Title' must contain a non-null value when exiting constructor. Consider declaring the property as nullable. [CS11Tests]csharp(CS8618)
Non-nullable property 'Author' must contain a non-null value when exiting constructor. Consider declaring the property as nullable. [CS11Tests]csharp(CS8618)

public class Article2
{
    public Article2(string title, string subtitle, string author, DateTime published)
    {
        Title = title;
        Subtitle = subtitle;
        Author = author;
        Published = published;
    }

    public Article2(string title, string author, DateTime published)
    {
        Title = title;
        Author = author;
        Published = published;
    }

    public string Title { get; set; }
    public string? Subtitle { get; set; }
    public string Author { get; set; }
    public DateTime Published { get; set; }
}

 Article2 article = new("C# 11 Required Keyword", "A new language feature", "Name",  new DateTime(2022, 11, 12));

 public string Title { get; set; } = default!;

public class Article3
{
    public required string Title { get; set; }
    public string? Subtitle { get; set; }
    public required string Author { get; set; }
    public DateTime Published { get; set; }
}

public class Book
{
    public Book() => Name = string.Empty;

    public Book(string name) => Name = name;

    public required string Name { get; set; }
}

Book book = new("Book's Name");

Required member 'Book.Name' must be set in the object initializer or attribute constructor. [CS11Tests]csharp(CS9035)

public class Book
{
    [SetsRequiredMembers]
    public Book() => Name = string.Empty;

    [SetsRequiredMembers]
    public Book(string name) => Name = name;

    public required string Name { get; set; }
}