Doc update : Refactor properties to use 'required' instead of nullable with null default

Author: niteshsinghal85

README.md

@@ -41,7 +41,7 @@ The following steps describe how to create a JSON:API project.
    public class Person : Identifiable<long>
    {
        [Attr] public string? FirstName { get; set; }
-       [Attr] public string LastName { get; set; } = null!;
+       [Attr] public required string LastName { get; set; }
        [HasMany] public ISet<Person> Children { get; set; } = new HashSet<Person>();
    }
    ```

docs/usage/common-pitfalls.md

@@ -17,7 +17,7 @@ Now let's try to define the resource classes:
 public sealed class WebCustomer : Identifiable<long>
 {
     [Attr]
-    public string Name { get; set; } = null!;
+    public required string Name { get; set; }
 
     [HasOne]
     public LoginAccount? Account { get; set; }
@@ -27,7 +27,7 @@ public sealed class WebCustomer : Identifiable<long>
 public sealed class AdminCustomer : Identifiable<long>
 {
     [Attr]
-    public string Name { get; set; } = null!;
+    public required string Name { get; set; }
 
     [Attr]
     public string? CreditRating { get; set; }
@@ -40,7 +40,7 @@ public sealed class AdminCustomer : Identifiable<long>
 public sealed class LoginAccount : Identifiable<long>
 {
     [Attr]
-    public string EmailAddress { get; set; } = null!;
+    public required string EmailAddress { get; set; }
 
     [HasOne]
     public ??? Customer { get; set; }

docs/usage/options.md

@@ -141,13 +141,13 @@ public class Person : Identifiable<long>
 {
     [Attr]
     [MinLength(3)]
-    public string FirstName { get; set; } = null!;
+    public required string FirstName { get; set; }
 
     [Attr]
     [Required]
     public int? Age { get; set; }
 
     [HasOne]
-    public LoginAccount Account { get; set; } = null!;
+    public required LoginAccount Account { get; set; }
 }
 ```

docs/usage/resources/attributes.md

@@ -11,7 +11,7 @@ public class Person : Identifiable<long>
     public string? FirstName { get; set; }
 
     [Attr]
-    public string LastName { get; set; } = null!;
+    public required string LastName { get; set; }
 }
 ```
 
@@ -54,7 +54,7 @@ Otherwise, the attribute is silently omitted.
 public class User : Identifiable<long>
 {
     [Attr(Capabilities = ~AttrCapabilities.AllowView)]
-    public string Password { get; set; } = null!;
+    public required string Password { get; set; }
 }
 ```
 

docs/usage/resources/inheritance.md

@@ -10,7 +10,7 @@ Resource classes can be part of a type hierarchy. For example:
 public abstract class Human : Identifiable<long>
 {
     [Attr]
-    public string Name { get; set; } = null!;
+    public required string Name { get; set; }
 
     [HasOne]
     public Man? Father { get; set; }

docs/usage/resources/nullability.md

@@ -72,13 +72,13 @@ Example:
 public sealed class Label : Identifiable<long>
 {
     [Attr]
-    public string Name { get; set; } = null!;
+    public required string Name { get; set; }
 
     [Attr]
     public string? RgbColor { get; set; }
 
     [HasOne]
-    public Person Creator { get; set; } = null!;
+    public required Person Creator { get; set; }
 
     [HasOne]
     public Label? Parent { get; set; }

docs/usage/resources/relationships.md

@@ -39,7 +39,7 @@ The next example defines that each car requires an engine, while an engine is op
 public sealed class Car : Identifiable<long>
 {
     [HasOne]
-    public Engine Engine { get; set; } = null!;
+    public required Engine Engine { get; set; }
 }
 
 public sealed class Engine : Identifiable<long>
@@ -264,7 +264,7 @@ There are two ways the exposed relationship name is determined:
 public class TodoItem : Identifiable<long>
 {
     [HasOne(PublicName = "item-owner")]
-    public Person Owner { get; set; } = null!;
+    public required Person Owner { get; set; }
 }
 ```
 
@@ -297,7 +297,7 @@ Otherwise, the relationship (and its related resources, when included) are silen
 public class User : Identifiable<long>
 {
     [HasOne(Capabilities = ~HasOneCapabilities.AllowView)]
-    public LoginAccount Account { get; set; } = null!;
+    public required LoginAccount Account { get; set; }
 }
 ```
 
@@ -339,7 +339,7 @@ Indicates whether POST and PATCH requests can replace the relationship. When sen
 public class User : Identifiable<long>
 {
     [HasOne(Capabilities = ~HasOneCapabilities.AllowSet)]
-    public LoginAccount Account { get; set; } = null!;
+    public required LoginAccount Account { get; set; }
 }
 ```
 
@@ -400,7 +400,7 @@ So for the calculated property to be evaluated correctly, the related entity mus
 public class ShippingAddress : Identifiable<long>
 {
     [Attr]
-    public string Street { get; set; } = null!;
+    public required string Street { get; set; }
 
     [Attr]
     public string? CountryName => Country?.DisplayName;
@@ -412,7 +412,7 @@ public class ShippingAddress : Identifiable<long>
 
 public class Country
 {
-    public string IsoCode { get; set; } = null!;
-    public string DisplayName { get; set; } = null!;
+    public required string IsoCode { get; set; }
+    public required string DisplayName { get; set; }
 }
 ```