Is multipart-formdata is supported in Pega7.3.1?

We have a requirement to send the document in Connect-REST as an attachment in request. Pega version is Pega7.3.1.

As per the help guide (https://customer-coml-dev731.cmp.dev.cba/prhelp/procomhelpmain.htm#rule-/rule-connect-/AttachmentsSOAPdotNetHttp.htm?Highlight=pyRequestAttachmentPage)  and multiple PDN forums, implemented as below. But it is not working.

pyRequestAttachmentPage is populated in prior to calling the Connect-REST and below are mappings.

Tried pyAttachTypes(1) = application/pdf, application/json and multipart/form-Data. But same error is received. Also, request is not having the Attachment details.

Error: As per the request from the Log file, there is no attachment in the Request body. Service provider system is not receiving the attachment.

------------------HTTP REQUEST CONTENTS------------------

Request Headers: {Authorization=Bearer eyJh, Content-Type=multipart/form-data; boundary=jeKANG1-9Ks5mMY_4WKNIQUgpBS4RZikIvU}

Request Message Data: 613834 bytes to be sent

<?xml version="1.0"?>

<pagedata>

<pxObjClass></pxObjClass>

<document>ABCD==</document>

<documentGuid>AD12345</documentGuid>

</pagedata>

------------------END HTTP REQUEST CONTENTS------------------

------------------HTTP RESPONSE CONTENTS------------------

Response Headers:

Connection: keep-alive

Content-Length: 675

Content-Type: application/json

vary: Origin

x-request-id: a95e32d7-9c54-45d9-8114-ff8db3ae9a0c#1012176

Response Message Data: 675 bytes received

{"entities":[],"entityConfidences":[],"modelMetadata":"....","pageFailures":[{"message":"unable to process file: unable to process file: no file content on input","pageIndex":"-1","type":"General"}],"pages":{}}

----------------END HTTP RESPONSE CONTENTS------