releaseDate property
optional Array of URL(s) to an image associated with the content. The initial value of the field can be provided by the sender in the Load message. Should provide recommended sizes optional ISO 8601 date and time this content was released. Player can independently retrieve releaseDate using content_id or it can be given by the sender in the Load message
Implementation
///optional ISO 8601 date and time
/// this content was released. Player
/// can independently retrieve releaseDate
/// using content_id or it can be given
/// by the sender in the Load message
final DateTime? releaseDate;