Repository: microsoft/kiota (csharp)

Issue:
Warnings about discriminator not being inherited 
Since commit 448af8fd37ada0e4f38379453d4739274ee72ccf (which is the first of [this pull request](https://github.com/microsoft/kiota/pull/4723)) I see a lot of warnings about discriminator not being inherited when generating my client. For example:

> Discriminator SObjectRootInfo is not inherited from SObjectRootInfo.

The generated code is identical, only the warnings are new.

This problem can be reproduced by debugging the `AddsDiscriminatorMappingsAllOfImplicit` test and setting a breakpoint on `logger.LogWarning("Discriminator {ComponentKey} is not inherited from {ClassName}.", componentKey, baseClass.Name);` in the KiotaBuilder.cs file.

_Originally posted by @0xced in https://github.com/microsoft/kiota/issues/4723#issuecomment-2137630398_

Pull request description:
Fixes https://github.com/microsoft/kiota/issues/4761

Patch:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 34e10fa314..a469a745b7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -46,6 +46,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixes a bug where indexers in include/exclude patters were not normalized if the indexer was the last segment without a slash at the end [#4715](https://github.com/microsoft/kiota/issues/4715)
 - Fixes a bug where CLI generation doesnot handle parameters of type string array. [#4707](https://github.com/microsoft/kiota/issues/4707)
 - Fixed a bug where models would not be created when a multipart content schema existed with no encoding [#4734](https://github.com/microsoft/kiota/issues/4734)
+- Fixes a bug where warnings about discriminator not being inherited were generated [#4761](https://github.com/microsoft/kiota/issues/4761)
 
 ## [1.14.0] - 2024-05-02
 
diff --git a/src/Kiota.Builder/KiotaBuilder.cs b/src/Kiota.Builder/KiotaBuilder.cs
index 81613e912f..226e831e78 100644
--- a/src/Kiota.Builder/KiotaBuilder.cs
+++ b/src/Kiota.Builder/KiotaBuilder.cs
@@ -2164,7 +2164,8 @@ internal static void AddDiscriminatorMethod(CodeClass newClass, string discrimin
         }
         if (baseClass is not null && (result.TypeDefinition is not CodeClass codeClass || codeClass.StartBlock.Inherits is null))
         {
-            logger.LogWarning("Discriminator {ComponentKey} is not inherited from {ClassName}.", componentKey, baseClass.Name);
+            if (!baseClass.Equals(result.TypeDefinition))// don't log warning if the discriminator points to the base type itself as this is implicitly the default case. 
+                logger.LogWarning("Discriminator {ComponentKey} is not inherited from {ClassName}.", componentKey, baseClass.Name);
             return null;
         }
         return result;


Test patch:
diff --git a/tests/Kiota.Builder.Tests/KiotaBuilderTests.cs b/tests/Kiota.Builder.Tests/KiotaBuilderTests.cs
index e70aff7d30..fc0df2d7d5 100644
--- a/tests/Kiota.Builder.Tests/KiotaBuilderTests.cs
+++ b/tests/Kiota.Builder.Tests/KiotaBuilderTests.cs
@@ -3426,6 +3426,13 @@ public async Task AddsDiscriminatorMappingsAllOfImplicit()
         var entityClass = codeModel.FindChildByName<CodeClass>("entity");
         var directoryObjectClass = codeModel.FindChildByName<CodeClass>("directoryObject");
         var userClass = codeModel.FindChildByName<CodeClass>("user");
+        mockLogger.Verify(logger => logger.Log(
+                It.Is<LogLevel>(logLevel => logLevel == LogLevel.Warning),
+                It.Is<EventId>(eventId => eventId.Id == 0),
+                It.Is<It.IsAnyType>((@object, @type) => @object.ToString().Contains(" is not inherited from ", StringComparison.OrdinalIgnoreCase) && @type.Name == "FormattedLogValues"),
+                It.IsAny<Exception>(),
+                It.IsAny<Func<It.IsAnyType, Exception, string>>()),
+            Times.Never);
         Assert.NotNull(entityClass);
         Assert.NotNull(directoryObjectClass);
         Assert.NotNull(userClass);