Multipart request rejected because no bounday were found while boundary is already sent - spring-boot

Question

I went through the other similar questions but couldn't find any solution. We have a backend service running by Spring Boot and has been working for a while now. But there is a new user of this service recently and they are using MuleSoft to send their request. But all attempts to send a file to our service fails with this error:
Failed to parse multipart servlet request; nested exception is java.io.IOException: org.apache.tomcat.util.http.fileupload.FileUploadException: the request was rejected because no multipart boundary was found"
The only difference we could find between a request from MuleSoft and say a curl command is that MuleSoft always sends the request with boundary value wrapped with double quotes
Mule request:
<Header name="Content-Type">multipart/form-data; charset=UTF-8; boundary="--------------------------669816398596264398718285"</Header>
Versus Postman/curl request:
* SSL certificate verify ok.
* Using HTTP2, server supports multiplexing
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x7fd656810a00)
> POST /api/upload HTTP/2
> Host: myhost
> user-agent: curl/7.79.1
> accept: */*
> content-length: 97255
> content-type: multipart/form-data; boundary=------------------------111fd08cb4fafe1c
>
* Connection state changed (MAX_CONCURRENT_STREAMS == 128)!
* We are completely uploaded and fine
< HTTP/2 200
< date: Mon, 19 Dec 2022 04:56:25 GMT
< content-length: 0
Our controller in Spring is very simple:
#RestController
class MyController {
#PostMapping("/upload", consumes = [MediaType.MULTIPART_FORM_DATA_VALUE])
#ResponseStatus(HttpStatus.OK)
fun uploadDocument(#RequestPart("file") file: MultipartFile) {
logger.info { "ContentType: ${file.contentType}" }
logger.info { "Name: ${file.name}" }
logger.info { "Byte: ${String(file.bytes)}" }
}
}
The following curl command works fine:
curl -v -X POST -F file=#/Users/myhomefolder/Documents/some-file.jpg https://host-name/api/upload
But this script from MuleSoft doesn't (Sorry I'm not familiar with Mule, I got this code from their team):
import dw::module::Multipart
output multipart/form-data boundary = "---WebKitFormBoundary7MA4YWxkTrZu0gW"
---
{
parts : {
file : {
headers : {
"Content-Disposition" : {
"name": "file",
"filename": payload.name
},
"Content-Type" : "multipart/form-data"
},
content : payload.byteArray
}
}
}
Is there any configuration in Spring that accepts double quotes for boundary? Is there anything missing in our backend configuration that should be added to support different HTTP client?