add null to writer methods

Author: shemogumbe

packages/serialization/multipart/src/multipartSerializationWriter.ts

@@ -6,7 +6,7 @@
  */
 
 /* eslint-disable @typescript-eslint/no-unused-expressions */
-import { type DateOnly, type Duration, MultipartBody, type Parsable, type SerializationWriter, type ModelSerializerFunction, type TimeOnly } from "@microsoft/kiota-abstractions";
+import { type DateOnly, type Duration, type Parsable, type SerializationWriter, type ModelSerializerFunction, type TimeOnly } from "@microsoft/kiota-abstractions";
 import type { Guid } from "guid-typescript";
 
 /** Serialization writer for multipart/form-data */