MultipartFormContentProcessor falls back to the Delegate Writer if none of the other writers can handle a field. The PojoWriter loops the other writers to handle fields in an object, but it does not fall back to the Delegate Writer.
I solved this by getting the MultipartFormContentProcessor out and adding the DelegateWriter to the list, so that it is passed to the PojoWriter instead of just being the fallback option
MultipartFormContentProcessor falls back to the Delegate Writer if none of the other writers can handle a field. The PojoWriter loops the other writers to handle fields in an object, but it does not fall back to the Delegate Writer. I solved this by getting the MultipartFormContentProcessor out and adding the DelegateWriter to the list, so that it is passed to the PojoWriter instead of just being the fallback option