We aim to have the same media item instance published in the timeline that is passed to the createMediaSource(mediaItem) method. This means when the manifest uri is manually replaced by a developer, the media item published in the next timeline update is still the same.
Note: This leads to the fact that the manifest published in that timeline is loaded from a different URI than the URI of the media item in the same timeline.
PiperOrigin-RevId: 313375421
