Adding more breaking changes info for EF Core 6.0

Fixes #3486
Fixes #3488
Fixes #3490

Author: maumar

entity-framework/core/what-is-new/ef-core-2.0/upgrade.md

@@ -2,7 +2,7 @@
 title: Upgrading from previous versions to EF Core 2 - EF Core
 description: Instructions and notes for upgrading to Entity Framework Core 2.0
 author: ajcvickers
-ms.date: 08/13/2017
+ms.date: 10/25/2021
 uid: core/what-is-new/ef-core-2.0/upgrade
 ---
 
@@ -138,6 +138,33 @@ optionsBuilder.UseInMemoryDatabase("MyDatabase");
 
 This creates/uses a database with the name “MyDatabase”. If `UseInMemoryDatabase` is called again with the same name, then the same in-memory database will be used, allowing it to be shared by multiple context instances.
 
+## In-memory provider 'Include' operation no longer returns results if the included navigation is required but its value is null
+
+When trying to include a required navigation and the included navigation is null, the query no longer returns result for the entity on which the Include operation is applied. To avoid this problem, either provide a value for the required navigation or change the navigation to be optional.
+
+```csharp
+public class Person
+{
+    public int Id { get; set; }
+    public Language NativeLanguage { get; set;} // required navigation
+    public Person Sibling { get; set; } // optional navigation
+}
+...
+var person = new Person();
+context.People.Add(person);
+context.SaveChanges();
+...
+
+// returns one result
+context.People.ToList();
+
+// returns no results because 'NativeLanguage' navigation is required but has not been provided
+context.People.Include(p => p.NativeLanguage).ToList(); 
+
+// returns one result because 'Sibling' navigation is optional so it doesn't have to be provided
+context.People.Include(p => p.Sibling).ToList(); 
+```
+
 ## Read-only API changes
 
 `IsReadOnlyBeforeSave`, `IsReadOnlyAfterSave`, and `IsStoreGeneratedAlways` have been obsoleted and replaced with [BeforeSaveBehavior](/dotnet/api/microsoft.entityframeworkcore.metadata.iproperty.beforesavebehavior) and [AfterSaveBehavior](/dotnet/api/microsoft.entityframeworkcore.metadata.iproperty.aftersavebehavior). These behaviors apply to any property (not only store-generated properties) and determine how the value of the property should be used when inserting into a database row (`BeforeSaveBehavior`) or when updating an existing database row (`AfterSaveBehavior`).

entity-framework/core/what-is-new/ef-core-6.0/breaking-changes.md

@@ -35,6 +35,8 @@ The following API and behavior changes have the potential to break existing appl
 | [`DbFunctionBuilder.HasSchema(null)` overrides `[DbFunction(Schema = "schema")]`](#function-schema)                                   | Low        |
 | [Pre-initialized navigations are overridden by values from database queries](#overwrite-navigations)                                  | Low        |
 | [Unknown enum string values in the database are not converted to the enum default when queried](#unknown-emums)                       | Low        |
+| [DbFunctionBuilder.HasTranslation now provides the function arguments as IReadOnlyList rather than IReadOnlyCollection](#func-args)   | Low        |
+| [Default table mapping is not removed when the entity is mapped to a table-valued function](#tvf-default-mapping)                     | Low        |
 
 \* These changes are of particular interest to authors of database providers and extensions.
 
@@ -757,3 +759,51 @@ Converting to the default value can result in database corruption if the entity
 #### Mitigations
 
 Ideally, ensure that the database column only contains valid values. Alternately, implement a `ValueConverter` with the old behavior.
+
+<a name="func-args"></a>
+
+### DbFunctionBuilder.HasTranslation now provides the function arguments as IReadOnlyList rather than IReadOnlyCollection
+
+[Tracking Issue #23565](https://github.com/dotnet/efcore/issues/23565)
+
+#### Old behavior
+
+When configuring translation for a user-defined function using `HasTranslation` method, the arguments to the function were provided as `IReadOnlyCollection<SqlExpression>`.
+
+#### New behavior
+
+In EF Core 6.0, the arguments are now provided as `IReadOnlyList<SqlExpression>`.
+
+#### Why
+
+`IReadOnlyList` allows to use indexers, so the arguments are now easier to access.
+
+#### Mitigations
+
+None. `IReadOnlyList` implements `IReadOnlyCollection` interface, so the transition should be straightforward.
+
+<a name="tvf-default-mapping"></a>
+
+### Default table mapping is not removed when the entity is mapped to a table-valued function
+
+[Tracking Issue #23408](https://github.com/dotnet/efcore/issues/23408)
+
+#### Old behavior
+
+When an entity was mapped to a table-valued function, its default mapping to a table was removed.
+
+#### New behavior
+
+In EF Core 6.0, the entity is still mapped to a table using default mapping, even if it's also mapped to table-valued function.
+
+#### Why
+
+Table-valued functions which return entities are often used either as a helper or to encapsulate an operation returning a collection of entities, rather than as a strict replacement of the entire table. This change aims to be more in line with the likely user intention.
+
+#### Mitigations
+
+Mapping to a table can be explicitly disabled in the model configuration:
+
+```csharp
+modelBuilder.Entity<MyEntity>().ToTable((string)null);
+```