Does the encode attachment InfoPath from Kotlin or Java have different signature from C#?

Question

I have encode the attachment InfoPath following the document from Microsoft attactment-infopath to Kotlin. The class produces different Strings from the C# code. I think because of the InfoPath signature. I want it the same String from C#.

Here is my class.

class InfoPathAttachmentEncoder(private val fullyQualifiedFileName: String) {

    private var base64EncodedFile = ""

    // Creates an encoder to create an InfoPath attachment string.
    init {
        if (fullyQualifiedFileName == "")
            throw IllegalArgumentException("Must specify file name")

        if (!File(fullyQualifiedFileName).exists())
            throw FileNotFoundException("File does not exist: $fullyQualifiedFileName")
    }

    // Returns a Base64 encoded string.
    fun toBase64String(): String {
        if (base64EncodedFile != "")
            return base64EncodedFile

        // This memory stream will hold the InfoPath file attachment buffer before Base64 encoding.
        val ms = ByteArrayOutputStream()

        // Get the file information.
        val f = File(fullyQualifiedFileName)
        DataInputStream(f.inputStream()).use { br ->
            val fileName = File(fullyQualifiedFileName).name

            val fileNameLength = fileName.length + 1

            val fileNameBytes = fileName.toByteArray(Charsets.UTF_16LE)

            DataOutputStream(ms).use { bw ->
                // Write the InfoPath attachment signature.
                bw.write(byteArrayOf(0xC7.toByte(), 0x49.toByte(), 0x46.toByte(), 0x41.toByte()))

                // Write the default header information.
                bw.writeInt(0x14)// size
                bw.writeInt(0x01)// version
                bw.writeInt(0x00)// reserved

                // Write the file size.
                bw.writeInt(f.length().toInt())

                // Write the size of the file name.
                bw.writeInt(fileNameLength)

                // Write the file name (Unicode encoded).
                bw.write(fileNameBytes)

                // Write the file name terminator. This is two nulls in Unicode.
                bw.write(byteArrayOf(0, 0))

                // Iterate through the file reading data and writing it to the outbuffer.
                val data = ByteArray(64 * 1024)

                var bytesRead: Int

                while (br.read(data, 0, data.size).also { bytesRead = it } > 0) {
                    bw.write(data, 0, bytesRead)
                }
            }
        }

        val encodedBytes = Base64.getEncoder().encode(ms.toByteArray())

        return String(encodedBytes, Charsets.US_ASCII)
    }
}

val i = InfoPathAttachmentEncoder(path)
println(">>>Endcoding {} ${i.toBase64String()}")

The result from C#: x0lGQRQAAAABAAAAAAAAAB8uAAAdAAAAQQB0AHQALQAyADAAMgAzAC0AMAA2AC0AMgA4ACAAMQA0AC0AMQAzAC0AMwA1AC4AZABvAGMAeAAAAFBLAwQUAAYACAAAACEA36TSbFoBAAAgBQAAEwAIAltDb250ZW50X1R5cGVzXS54bWwgogQCKK...

The result from Kotlin: x0lGQQAAABQAAAABAAAAAAAALh8AAAAdQQB0AHQALQAyADAAMgAzAC0AMAA2AC0AMgA4ACAAMQA0AC0AMQAzAC0AMwA1AC4AZABvAGMAeAAAAFBLAwQUAAYACAAAACEA36TSbFoBAAAgBQAAEwAIAltDb250ZW50X1R5cGVzXS54bWwgogQCKK...

The bolded characters here is the different String.