Create retrofit Multi Part api call to upload cert file

MultiPart Upload PFX file

@POST("api/v1/testApp/sign")
@Multipart
suspend fun sign(
    @Part certFile: MultipartBody.Part,
    @Part passwordFile: MultipartBody.Part,
    @Part("data") data: RequestBody
): Response<CustomResponseModel>


private fun readPfxFileFromAssets(context: Context, fileName: String): ByteArray {
    val inputStream: InputStream = context.assets.open(fileName)
    val buffer = ByteArrayOutputStream()
    val bufferSize = 1024
    val bufferData = ByteArray(bufferSize)
    var bytesRead: Int

    while (inputStream.read(bufferData, 0, bufferSize).also { bytesRead = it } != -1) {
        buffer.write(bufferData, 0, bytesRead)
    }

    return buffer.toByteArray()
}

private fun createPfxFilePart(context: Context, fileName: String): MultipartBody.Part {
    val pfxFileData = readPfxFileFromAssets(context, fileName)
//    val base64 = Base64.encodeToString(pfxFileData, Base64.NO_WRAP)
    val requestBody = RequestBody.create("application/x-pkcs12".toMediaTypeOrNull(), pfxFileData)
    return createFormData("CertFile", fileName, requestBody)
}

private const val MULTIPART_FILE_CONTENT_TYPE = "application/x-pkcs12"
private const val MULTIPART_DATA_CONTENT_TYPE = "application/json"
private const val CERT_FILE_NAME = "myCert.pfx"

val requestBody = RequestBody.create(
            MULTIPART_FILE_CONTENT_TYPE.toMediaTypeOrNull(),
            Base64.decode(CERT_BASE64, Base64.NO_WRAP)
        )
        val pfxFilePart = createFormData("CertFile", CERT_FILE_NAME, requestBody)

        val dataRequestBody: RequestBody =
            jsonString.toRequestBody(MULTIPART_DATA_CONTENT_TYPE.toMediaTypeOrNull())

        val generalResponseModel = service.sign(
            certFile = pfxFilePart,
            passwordFile = createFormData("PasswordFile", MULTIPART_FILE_PASSWORD),
            data = dataRequestBody
        )