addNewPlayers
public static boolean addNewPlayers(Collection<Player> requestedPlayers, MatchInstance matchInstance)
Atomically admits a set of players. Every check and every cancellable join event runs for the whole group before any state changes, so a party is never split by a full instance, missing permission, another active match, or an API veto.
public static boolean addNewPlayers(Collection<Player> requestedPlayers, MatchInstance matchInstance, BooleanSupplier authorization)
Atomically admits players while an external authorization remains valid. The predicate is rechecked after the cancellable join events so they cannot revive a cancelled party launch.