Cannot open the file under `getExternalFilesDir` for saving image in image editor

[wangyung]

when using withOutput(File) or withOutput(Uri), as long as the file or uri is under the path of getExternalFilesDir(). There is always an exception like this

E/HiResBackgroundService: handled save error: com.adobe.creativesdk.aviary.internal.headless.AdobeImageExecutionException: File not loaded
E/HiResBackgroundService: dispatchError: 3
W/System.err: com.adobe.creativesdk.aviary.internal.headless.AdobeImageExecutionException: File not loaded
W/System.err:     at com.adobe.creativesdk.aviary.internal.services.HiResBackgroundService$InternalHandler.saveImage(HiResBackgroundService.java:217)
W/System.err:     at com.adobe.creativesdk.aviary.internal.services.HiResBackgroundService$InternalHandler.handleMessage(HiResBackgroundService.java:196)
W/System.err:     at android.os.Handler.dispatchMessage(Handler.java)
W/System.err:     at android.os.Looper.loop(Looper.java)
W/System.err:     at android.os.HandlerThread.run(HandlerThread.java)

Guess it is a permission issue, but add Intent.FLAG_GRANT_WRITE_URI_PERMISSION doesn't help. What should I do in the SDK?