Android downloaded zip file every time damaged

Question

I have problem with download file from ftp server using library commons-net-3.6-ftp. Every time when I download always missing about 2kb with original size.

    fun download(url: MapFragment){
        try {
            ftpClient?.changeWorkingDirectory("mapa/"+url.shortName)

            listener!!.mapDownloadStarted()
            val pathh = this.context!!.getExternalFilesDir(null)
            val test = ftpClient?.listFiles()

            test?.forEach {
                val fileObj = File(pathh, "ptv/maps/" + it.name)

                val desFileStream = BufferedOutputStream(FileOutputStream(fileObj))
                val input: InputStream = ftpClient!!.retrieveFileStream(it.name)

                try {
                    org.apache.commons.net.io.Util.copyStream(input,desFileStream)
                    desFileStream.flush()
                    desFileStream.close()
                    ftpClient!!.disconnect()
                } catch (e: IOException) {
                    e.printStackTrace()
                }
            }
        }catch (e: Exception) {
            logE(e.toString())
        }
    }

configuration

val pass = context.getString(R.string.passFtp)
                val loginFtp = context.getString(R.string.userFtp)
                val serverFtp = context.getString(R.string.serverFtp)
                val mFtpClient = FTPSClient()
                val sc = SSLContext.getInstance("SSL")
                val sr = java.security.SecureRandom()
                sc.init(null, getTrustManager(), sr)
                mFtpClient.connect(serverFtp, 62023)
                mFtpClient.setDataTimeout(25000)
                mFtpClient.bufferSize = 1024 * 1024
                mFtpClient.setFileType(FTP.BINARY_FILE_TYPE)
                mFtpClient.execPBSZ(0)
                mFtpClient.execPROT("P")
                mFtpClient.enterLocalPassiveMode()

if (mFtpClient.login(loginFtp, pass)) {
                    ftpClient = mFtpClient
                } else {
                    ftpClient = null
                }

I used retriveFile instead retrieveFileStream but everytime missing around 2kb