Fix/go package name casing

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Fix package casing normalizing for value passed using `--namespace-name` option when generating Go Client. [#4498](https://github.com/microsoft/kiota/issues/4498)
 - Aligns naming of sliced OpenAPI description generated by `plugin add` should be named `<plugin-name>-openapi.json|yml` [#4595](https://github.com/microsoft/kiota/issues/4595)
 - Fixed RPC server to respect the `KIOTA_CONFIG_PREVIEW` flag.
 - Added missing nullable directives for CLI generation.

src/Kiota.Builder/Refiners/GoRefiner.cs

@@ -19,6 +19,7 @@
         {
             cancellationToken.ThrowIfCancellationRequested();
             DeduplicateErrorMappings(generatedCode);
+            NormalizeNamespaceNames(generatedCode);
             MoveRequestBuilderPropertiesToBaseType(generatedCode,
                 new CodeUsing
                 {
@@ -45,7 +46,7 @@
                 string.Empty,
                 false,
                 MergeOverLappedStrings);
             if (_configuration.ExcludeBackwardCompatible) //TODO remove condition for v2
                 RemoveRequestConfigurationClasses(generatedCode,
                     new CodeUsing
                     {
@@ -182,7 +183,7 @@
             );
             AddParsableImplementsForModelClasses(
                 generatedCode,
                 "Parsable"
             );
             RenameInnerModelsToAppended(
                 generatedCode
@@ -239,7 +240,7 @@
         return $"{start}{end}";
     }
 
     private void CorrectBackingStoreTypes(CodeElement currentElement)
     {
         if (!_configuration.UsesBackingStore)
             return;
@@ -380,7 +381,7 @@
             .ToList();
 
         // check if the last element contains current name and remove it
         if (namespacePathSegments.Count > 0 && removeDuplicate && fileName.ToFirstCharacterUpperCase().Contains(namespacePathSegments.Last(), StringComparison.Ordinal))
             namespacePathSegments.RemoveAt(namespacePathSegments.Count - 1);
 
         namespacePathSegments.Add(fileName.ToFirstCharacterUpperCase());
@@ -544,7 +545,7 @@
         "UUID",
         "Guid"
     };
     private static readonly AdditionalUsingEvaluator[] defaultUsingEvaluators = {
         new (static x => x is CodeProperty prop && prop.IsOfKind(CodePropertyKind.RequestAdapter),
             AbstractionsNamespaceName, "RequestAdapter"),
         new (static x => x is CodeMethod method && method.IsOfKind(CodeMethodKind.RequestGenerator),
@@ -602,7 +603,7 @@
         block.ReplaceImplementByName(KiotaBuilder.AdditionalHolderInterface, "AdditionalDataHolder");
         block.ReplaceImplementByName(KiotaBuilder.BackedModelInterface, "BackedModel");
     }
     private static void CorrectMethodType(CodeMethod currentMethod)
     {
         var parentClass = currentMethod.Parent as CodeClass;
         if (currentMethod.IsOfKind(CodeMethodKind.RequestGenerator, CodeMethodKind.RequestExecutor))
@@ -757,4 +758,25 @@
         }
         CrawlTree(currentElement, RenameInnerModelsToAppended);
     }
+
+    private void NormalizeNamespaceNames(CodeElement currentElement)
+    {
+        if (currentElement is CodeNamespace codeNamespace)
+        {
+            var clientNamespace = _configuration.ClientNamespaceName;
+            var namespaceName = codeNamespace.Name;
+            if (namespaceName.StartsWith(clientNamespace, StringComparison.OrdinalIgnoreCase) && !namespaceName.Equals(clientNamespace, StringComparison.OrdinalIgnoreCase))
+            {
+                var secondPart = namespaceName[clientNamespace.Length..]; // The rest of the name after the clientNamespace
+                var withEmptyRemoved = string.Join('.', secondPart.Split('.', StringSplitOptions.RemoveEmptyEntries));
+                var normalizedString = string.IsNullOrEmpty(withEmptyRemoved) switch
+                {
+                    true => string.Empty,
+                    false => $".{withEmptyRemoved}"
+                };
+                codeNamespace.Name = $"{clientNamespace}{normalizedString.ToLowerInvariant()}";
+            }
+        }
+        CrawlTree(currentElement, NormalizeNamespaceNames);
+    }
 }

src/Kiota.Builder/Writers/Go/GoNamespaceExtensions.cs

@@ -12,14 +12,14 @@
         if (string.IsNullOrEmpty(nsName)) return string.Empty;
         var urlPrefixIndex = nsName.LastIndexOf('/') + 1;
         var tentativeSegment = nsName[urlPrefixIndex..].Split('.', StringSplitOptions.RemoveEmptyEntries).LastOrDefault();
         if (string.IsNullOrEmpty(tentativeSegment)) tentativeSegment = nsName.Split('/', StringSplitOptions.RemoveEmptyEntries).Last();
-        return tentativeSegment.ToLowerInvariant();
+        return tentativeSegment;
     }
     public static string GetInternalNamespaceImport(this CodeElement ns)
     {
         if (ns == null) return string.Empty;
         var urlPrefixIndex = ns.Name.LastIndexOf('/') + 1;
-        return (ns.Name[..urlPrefixIndex] + string.Join("/", ns.Name[urlPrefixIndex..].Split('.', StringSplitOptions.RemoveEmptyEntries))).ToLowerInvariant();
+        return (ns.Name[..urlPrefixIndex] + string.Join("/", ns.Name[urlPrefixIndex..].Split('.', StringSplitOptions.RemoveEmptyEntries)));
     }
     public static string GetNamespaceImportSymbol(this CodeElement ns)
     {