public void makeImmutable(){
  if (mutable && (authenticatingAuthority != null)) {
    authenticatingAuthority=Collections.unmodifiableList(authenticatingAuthority);
  }
  mutable=false;
}

public void makeImmutable ( ) { if ( mutable && ( authenticatingAuthority != null ) ) { authenticatingAuthority = Collections . unmodifiableList ( authenticatingAuthority ) ; } mutable = false ; }
makes the object immutable .
