Incorrect content type in method `_download(..)` in `ClientHTTPConnection.java`

[ZeroZill]

Description

There is something wrong when getting the contentType in _download(...) method.

Expected behavior

While receiving an audio message, the contentType should be one of the types in AudioComponent's MIME_TYPES, so the destination of received file can be confirmed.

Actual behavior

The content type we got is video/mp4, which is not in MIME_TYPES, thus the destination was assigned to be null.

Steps to reproduce

1. Add a break point in method _download(..) and run app in debug mode.
2. Record an audio and send it to a contact.
3. Receive this message and then check the value of contentType in debug mode.

Environment

Kontalk version: 4.4.0 Google

Android version: Android 10.0

Device: Google Pixel 2