Kotlin Retrofit2 RequestBody from FileDescriptor

RequestBodyExt.kt

fun requestBody(fd: FileDescriptor) = object : RequestBody() {
  
  override fun contentType(): MediaType = MediaType.parse("multipart/form-data")
        
  override fun writeTo(sink: BufferedSink) {
    Okio.source(FileInputStream(fd)).use { source ->
      sink.writeAll(source)
    }
  }
}

Should not pass FileDescriptor around, because its owner ParcelFileDescriptor/AssetFileDescriptor must be closed when FileDescriptor InputStream is closed.
Better way is passing Uri and create ParcelFileDescriptor/AssetFileDescriptor when you need InputStream then close ParcelFileDescriptor/AssetFileDescriptor. (AutoCloseInputStream (ParcelFileDescriptor/AssetFileDescriptor) class can be used for closing)