Preparation for GA release of System.ClientModel (#49809)

* prep for GA release of System.ClientModel

* add some additional changelog entries

* one more changelog entry

* and another changelog entry

Author: m-redding

sdk/core/System.ClientModel/CHANGELOG.md

@@ -1,15 +1,22 @@
 # Release History
 
-## 1.4.0-beta.7 (Unreleased)
+## 1.4.0 (2025-05-02)
 
 ### Features Added
 
-### Breaking Changes
-
-### Bugs Fixed
+- Added additional supported scenarios to System.ClientModel.SourceGeneration.
 
 ### Other Changes
 
+- Upgraded versions of dependencies on System.Diagnostics.DiagnosticSource, System.Text.Json, and Microsoft.Extensions.Logging.Abstractions.
+- Renamed `ActivityExtensions.MarkFailed` to `ActivityExtensions.MarkClientActivityFailed`.
+- Made `int maxSize` parameter to `ClientCache` constructor required and removed default value.
+- Changed `IEquatable<object> clientId` parameter to `object clientId` in `ClientCache.GetClient`
+- Renamed `ConnectionCollection` to `ClientConnectionCollection`
+- Renamed `ConnectionProvider` to `ClientConnectionProvider`
+- Renamed `ToCollection` to `ConvertCollectionBuilder` in `ModelReadWriteTypeBuilder`
+- Renamed `AddKeyValuePair` to `AddItemWithKey` in `ModelReadWriteTypeBuilder`
+
 ## 1.4.0-beta.6 (2025-04-28)
 
 ### Features Added

sdk/core/System.ClientModel/src/System.ClientModel.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <Description>Contains building blocks for clients that call cloud services.</Description>
-    <Version>1.4.0-beta.7</Version>
+    <Version>1.4.0</Version>
     <!--The ApiCompatVersion is managed automatically and should not generally be modified manually.-->
     <ApiCompatVersion>1.3.0</ApiCompatVersion>
     <Nullable>enable</Nullable>