File input not working for api which I made using spring boot using kotlin

Question

I made one API in spring boot using Kotlin. In which one should pass a file in the form-data.

@PostMapping("/refunds")
fun uploadFileToS3(@RequestPart("file") file
                   : MultipartFile)
    : ResponseEntity<String> {
    if (!isCsvOrTsvOrExcel(file)) {
        throw Exception("Only CSV, TSV and xlsx files are allowed")
    }

    val key = "refunds/${file.originalFilename}" // TODO("add some randomness
                                                   // in file name")
        val fileUriAndRows =
            uploadFileService.uploadFileToS3(file, bucketName, key)

                val submerchantIds =
                userSubmerchantMapService.findByUserId(getCurrentUserLogin())
                    .get()
                    .map{it.submerchantId.toInt()}

                uploadFileService.saveData(file,
                    FileUploadDto(userId = getCurrentUserLogin().toInt(),
                        entityType = EntityType.REFUND.type,
                        status = DownloadStatus.PENDING.status,
                        referenceId = null, // TODO(vijay to input)
                        submerchantIds = submerchantIds,
                        requestedAt = LocalDateTime.now(),
                        totalRecords = fileUriAndRows.second,
                        inputFileName = file.originalFilename,
                        s3InputFileUrl = fileUriAndRows.first.toString()))

                    return ResponseEntity(
                        "File uploaded successfully: ${fileUriAndRows.first}",
                        HttpStatus.OK)
}

I have provided the api code above. I am calling the api using postman here is the ss of the api call that I am making.

content type header is automatically getting set by postman - value -> multipart/form-data; boundary=<calculated when request is sent> You can see in the ss I am sending the correct key "file".

I am getting this error -> 2025-02-26T12:50:15.552+05:30 WARN 553330 --- [command-center] [nio-8888-exec-1] .m.m.a.ExceptionHandlerExceptionResolver : Resolved [org.springframework.web.multipart.support.MissingServletRequestPartException: Required part 'file' is not present.]

I want to send the file in the api call. But above mentioned error is being throw and control never comes inside the controller function (verified this by adding debugger) that I provided above. I dont know why this error is being thrown. I am passing the correct key. What am I missing?

I want this api to work. Atleast control should come inside the controller function.