For you, wesley

master.java

public List<UUID> masters;

private void createMasterList() {
  this.masters = new ArrayList<UUID>();
}

private List<UUID> getMasters() {
  return this.masters;
}

public void addMaster(UUID player) {
  getMasters().add(player);
}
 
public boolean isMaster(UUID player) {
  return getMasters().contains(player);
}