requiredAudioChannels property
Channels the store requires, or null when it states no rule.
Apple asks for stereo and enforces it — with MOV_RESAVE_STEREO, after
the upload, naming a channel layout even for a file carrying no audio at
all. Nullable because a second store may not care, and a check that
invented a requirement would refuse a file nobody's rules refuse.
Implementation
final int? requiredAudioChannels;