onCreditChanged
Called when the current credit changes. This can occur due to several reasons:
Automatic playback: the player's position progresses naturally during playback and enters a new chapter.
Seeking: the user manually seeks to a new position within the content, landing within a different chapter.
Playlist change: the current playlist is changed, potentially resulting in a different set of chapters and a new active chapter.
Parameters
credit
The currently active Credit. This will be null if the current playback position is not within any defined credit.