feat(.NET): Update migration guide for 4.x

docs/platforms/dotnet/migration/index.mdx

@@ -6,6 +6,138 @@ sidebar_order: 8000
 
 Upgrading includes both breaking changes and new features.
 
+## Migrating to 4.x
+
+### .NET target framework changes
+
+We're dropping support for some of the old target frameworks, please check this [GitHub Discussion](https://github.com/getsentry/sentry-dotnet/discussions/2776) for details on why.
+
+- Support for .NET Framework 4.6.1 has been replaced with 4.6.2 
+<br/>.NET Framework 4.6.1 was announced on Nov 30, 2015. And went out of support over a year ago, on Apr 26, 2022.
+- Support for .NET Core 3.1 and .NET 5 has been dropped
+- Support for netstandard2.0 for Sentry.AspNetCore has been dropped
+- Support for .NET 6 on mobile (e.g: `net6.0-android`) has been replaced with .NET 7 
+<br/>.NET 6 on mobile has been out of support since May 2023 and with .NET 8, it's no longer possible to build .NET 6 Mobile specific targets. For that reason, we're moving the mobile-specific TFMs from `net6.0-platform` to `net7.0-platform`. Mobile apps still work on .NET 6 will pull the `Sentry` .NET 6, which offers the .NET-only features, without native/platform-specific bindings and SDKs. See [this ticket for more details](https://github.com/getsentry/sentry-dotnet/issues/2623).
+- Support for MAUI Tizen has been dropped
+
+### Sentry Self-hosted Compatibility
+
+If you're using `sentry.io` this change does not affect you.
+This SDK version is compatible with a self-hosted version of Sentry `22.12.0` or higher. If you are using an older version of [self-hosted Sentry](https://develop.sentry.dev/self-hosted/) (aka on-premise), you will need to [upgrade](https://develop.sentry.dev/self-hosted/releases/). 
+
+### Significant change in behavior
+
+- Transaction names for ASP.NET Core are now consistently named `HTTP-VERB /path` (e.g. `GET /home`). Previously, the leading forward slash was missing for some endpoints.
+- Setting `SentryOptions.Dsn` to `null` now throws `ArgumentNullException` during initialization.
+- Enable `CaptureFailedRequests` by default
+- Added `Sentry` namespace to global usings when `ImplicitUsings` is enabled
+If you have conflicts, you can opt out by adding the following to your `csproj`:
+```
+<PropertyGroup>
+  <SentryImplicitUsings>false</SentryImplicitUsings>
+</PropertyGroup>
+```
+- Transactions' spans are no longer automatically finished with the status `deadline_exceeded` by the transaction. This is now handled by the [Relay](https://github.com/getsentry/relay). 
+  - Customers self hosting Sentry must use verion 22.12.0 or later
+- The `User.IpAddress` is now set to `{{auto}}` by default, even when sendDefaultPII is disabled
+  - The "Prevent Storing of IP Addresses" option in the "Security & Privacy" project settings on sentry.io can be used to control this instead
+- The `DiagnosticLogger` signature for `LogWarning` changed to take the `exception` as the first parameter. That way it no longer gets mixed up with the TArgs.
+
+### Breaking Changes
+
+#### Changed APIs
+
+- Class renamed `Sentry.User` to `Sentry.SentryUser`
+- Class renamed `Sentry.Runtime` to `Sentry.SentryRuntime`
+- Class renamed `Sentry.Span` to `Sentry.SentrySpan`
+- Class renamed `Sentry.Transaction` to `Sentry.SentryTransaction`
+- Class renamed `Sentry.Constants` to `Sentry.SentryConstants`
+- Class renamed `Sentry.Context` to `Sentry.SentryContext`
+- Class renamed `Sentry.Package` to `Sentry.SentryPackage`
+- Class renamed `Sentry.Request` to `Sentry.SentryRequest`
+- Class renamed `Sentry.` to `Sentry.SentryTransaction`
+- Class renamed `Sentry.Session` to `Sentry.SentrySession`
+- Class renamed `Sentry.Attachment` to `Sentry.SentryAttachment`
+- Class renamed `Sentry.Hint` to `Sentry.SentryHint`
+- Interface renamed `Sentry.ISession` to `Sentry.SentryISession`
+- Interface renamed `Sentry.IJsonSerializable` to `Sentry.SentryIJsonSerializable`
+- Interface renamed `Sentry.ITransaction` to `Sentry.ITransactionTracer`.
+- Rename iOS and MacCatalyst platform-specific options from `Cocoa` to `Native`
+- Rename iOS platform-specific options `EnableCocoaSdkTracing` to `EnableTracing`
+- Rename Android platform-specific options from `Android` to `Native`
+- Rename Android platform-specific options `EnableAndroidSdkTracing` and `EnableAndroidSdkBeforeSend` to `EnableTracing` and `EnableBeforeSend` respectively
+- Rename iOS and MacCatalyst platform-specific options from `iOS` to `Cocoa`
+- `DebugImage` and `DebugMeta` moved to `Sentry.Protocol` namespace.
+- `SentryClient.Dispose` is no longer obsolete
+- `ISentryClient.CaptureEvent` overloads have been replaced by a single method accepting optional `Hint` and `Scope` parameters. You will need to pass `hint` as a named parameter from code that calls `CaptureEvent` without passing a `scope` argument.
+- `TransactionContext` and `SpanContext` constructors were updated. If you're constructing instances of these classes, you will need to adjust the order in which you pass parameters to these.
+- The `DiagnosticLogger` signature for `LogError` and `LogFatal` changed to take the `exception` as the first parameter. That way it no longer gets mixed up with the TArgs. The `DiagnosticLogger` now also receives an overload for `LogError` and `LogFatal` that accepts a message only.
+- `Distribution` added to `IEventLike`.
+- `StackFrame`'s `ImageAddress`, `InstructionAddress`, and `FunctionId` changed to `long?`.
+- `DebugImage.ImageAddress` changed to `long?`.
+- Contexts now inherit from `IDictionary` rather than `ConcurrentDictionary`. The specific dictionary being used is an implementation detail.
+- The method used to configure a Sentry Sink for Serilog now has an additional overload. Calling `WriteTo.Sentry()` with no arguments will no longer attempt to initialize the SDK (it has optional arguments to configure the behavior of the Sink only). If you want to initialize Sentry at the same time you configure the Sentry Sink then you will need to use the overload of this method that accepts a DSN as the first parameter (e.g. `WriteTo.Sentry("https://[email protected]:65535/2147483647")`).
+
+#### Removed APIs
+
+- SentrySinkExtensions.ConfigureSentrySerilogOptions is now internal. If you were using this method, please use one of the `SentrySinkExtensions.Sentry` extension methods instead.
+- A number of `[Obsolete]` options have been removed
+  - `BeforeSend` - use `SetBeforeSend` instead.
+  - `BeforeSendTransaction` - use `SetBeforeSendTransaction` instead.
+  - `BeforeBreadcrumb` - use `SetBeforeBreadcrumb` instead.
+  - `CreateHttpClientHandler` - use `CreateHttpMessageHandler` instead.
+  - `ReportAssemblies` - use `ReportAssembliesMode` instead.
+  - `KeepAggregateException` - this property is no longer used and has no replacement.
+  - `DisableTaskUnobservedTaskExceptionCapture` method has been renamed to `DisableUnobservedTaskExceptionCapture`.
+  - `DebugDiagnosticLogger` - use `TraceDiagnosticLogger` instead.
+- A number of iOS/Android-specific `[Obsolete]` options have been removed
+  - `Distribution` - use `SentryOptions.Distribution` instead.
+  - `EnableAutoPerformanceTracking` - use `SetBeforeSendTransaction` instead.
+  - `EnableCoreDataTracking` - use `EnableCoreDataTracing` instead.
+  - `EnableFileIOTracking` - use `EnableFileIOTracing` instead.
+  - `EnableOutOfMemoryTracking` - use `EnableWatchdogTerminationTracking` instead.
+  - `EnableUIViewControllerTracking` - use `EnableUIViewControllerTracing` instead.
+  - `StitchAsyncCode` - no longer available.
+  - `ProfilingTracesInterval` - no longer available.
+  - `ProfilingEnabled` - use `ProfilesSampleRate` instead.
+- Obsolete `SystemClock` constructor removed, use `SystemClock.Clock` instead.
+- Obsolete `Runtime.Clone()` removed, this shouldn't have been public in the past and has no replacement.
+- Obsolete `SentryException.Data` removed, use `SentryException.Mechanism.Data` instead.
+- Obsolete `AssemblyExtensions` removed, this shouldn't have been public in the past and has no replacement.
+- Obsolete `SentryDatabaseLogging.UseBreadcrumbs()` removed, it is called automatically and has no replacement.
+- Obsolete `Scope.GetSpan()` removed, use `Span` property instead.
+- Obsolete `IUserFactory` removed, use `ISentryUserFactory` instead.
+- `IHasMeasurements` has been removed, use `ISpanData` instead.
+- `IHasBreadcrumbs` has been removed, use `IEventLike` instead.
+- `ISpanContext` has been removed, use `ITraceContext` instead.
+- `IHasTransactionNameSource` has been removed, use `ITransactionContext` instead.
+- The unused `StackFrame.InstructionOffset` has been removed.
+- The unused `Scope.Platform` property has been removed.
+- The obsolete setter `Sentry.PlatformAbstractions.Runtime.Identifier` has been removed
+- `Sentry.Values<T>` is now internal as it is never exposed in the public API
+- The `TracePropagationTarget` class has been removed, use the `SubstringOrRegexPattern` class instead.
+- The `WithScope` and `WithScopeAsync` methods have been removed. We have discovered that these methods didn't work correctly in certain desktop contexts, especially when using a global scope.
+<br/>Replace your usage of `WithScope` with overloads of `Capture*` methods:
+  - `SentrySdk.CaptureEvent(SentryEvent @event, Action<Scope> scopeCallback)`
+  - `SentrySdk.CaptureMessage(string message, Action<Scope> scopeCallback)`
+  - `SentrySdk.CaptureException(Exception exception, Action<Scope> scopeCallback)`
+
+  ```c#
+  // Before
+  SentrySdk.WithScope(scope =>
+  {
+    scope.SetTag("key", "value");
+    SentrySdk.CaptureEvent(new SentryEvent());
+  });
+
+  // After
+  SentrySdk.CaptureEvent(new SentryEvent(), scope =>
+  {
+    // Configure your scope here
+    scope.SetTag("key", "value");
+  });
+  ```
+
 ## Migrating to 3.12.0
 
 ### NuGet Changes