Fixes inheritance evaluation when a referenced schema in an allOf

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Fixed a bug in generation when a referenced schema in an allOf was a primitive [#5701](https://github.com/microsoft/kiota/issues/5701).
+
 ## [1.21.0] - 2024-12-05
 
 ### Added

src/Kiota.Builder/Extensions/OpenApiSchemaExtensions.cs

@@ -77,7 +77,11 @@ public static bool IsInclusiveUnion(this OpenApiSchema? schema, uint exclusiveMi
     public static bool IsInherited(this OpenApiSchema? schema)
     {
         if (schema is null) return false;
-        var meaningfulMemberSchemas = schema.AllOf.FlattenSchemaIfRequired(static x => x.AllOf).Where(static x => x.IsSemanticallyMeaningful(ignoreEnums: true, ignoreArrays: true, ignoreType: true)).ToArray();
+        var meaningfulMemberSchemas = schema.AllOf.FlattenSchemaIfRequired(static x => x.AllOf)
+                                                                .Where(static x => x.IsSemanticallyMeaningful(ignoreEnums: true, ignoreArrays: true, ignoreType: true))
+                                                                // the next line ensures the meaningful schema are objects as it won't make sense inheriting from a primitive despite it being meaningful.
+                                                                .Where(static x => string.IsNullOrEmpty(x.Reference?.Id) || string.IsNullOrEmpty(x.Type) || "object".Equals(x.Type, StringComparison.OrdinalIgnoreCase))
+                                                                .ToArray();
         var isRootSchemaMeaningful = schema.IsSemanticallyMeaningful(ignoreEnums: true, ignoreArrays: true, ignoreType: true);
         return meaningfulMemberSchemas.Count(static x => !string.IsNullOrEmpty(x.Reference?.Id)) == 1 &&
             (meaningfulMemberSchemas.Count(static x => string.IsNullOrEmpty(x.Reference?.Id)) == 1 ||

tests/Kiota.Builder.Tests/Extensions/OpenApiSchemaExtensionsTests.cs

@@ -567,6 +567,32 @@ public void IsIntersection()
         };
         Assert.False(schema.IsInherited());
         Assert.False(schema.IsIntersection());
+
+        schema = new OpenApiSchema
+        {
+            Title = "Trader Id",
+            AllOf = new List<OpenApiSchema> {
+                new ()
+                {
+                    Title = "UserId",
+                    Description = "unique identifier",
+                    Type = "string",
+                    Pattern = "^[1-9][0-9]*$",
+                    Example = new OpenApiString("1323232"),
+                    Reference = new OpenApiReference
+                    {
+                        Id = "UserId" // This property makes the schema "meaningful"
+                    }
+                }
+            },
+            Reference = new OpenApiReference
+            {
+                Id = "TraderId" // This property makes the schema "meaningful"
+            }
+        };
+
+        Assert.False(schema.IsInherited());
+        Assert.False(schema.IsIntersection());
     }
     [Fact]
     public void MergesIntersection()