fix: missing properties in python when no additional properties

Signed-off-by: Vincent Biret <[email protected]>

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Fixed a bug where properties would be missing in Python models if they didn't have additional properties. [#5037](https://github.com/microsoft/kiota/issues/5037)
 - Fixed a bug in dotnet where CS1587 warnings are generated in generated enums with descriptions [#4957](https://github.com/microsoft/kiota/issues/4957)
 - Fixed a bug where the copilot teams toolkit integration would serialize empty declarative copilots. [#4974](https://github.com/microsoft/kiota/issues/4974)
 - Fixed a bug for the docker image where the volume path would not match the expected configuration for the description.

src/Kiota.Builder/Refiners/PythonRefiner.cs

@@ -288,6 +288,10 @@ private static void CorrectPropertyType(CodeProperty currentProperty)
             if (!string.IsNullOrEmpty(currentProperty.DefaultValue))
                 currentProperty.DefaultValue = "{}";
         }
+        else if (currentProperty.Kind is CodePropertyKind.Custom && currentProperty.Type.IsNullable && string.IsNullOrEmpty(currentProperty.DefaultValue))
+        {
+            currentProperty.DefaultValue = "None";
+        }
         currentProperty.Type.Name = currentProperty.Type.Name.ToFirstCharacterUpperCase();
         CorrectCoreTypes(currentProperty.Parent as CodeClass, DateTypesReplacements, currentProperty.Type);
     }