if (!elements.contains (o))
if (!this.elements.contains (o))
    SecureSet (final Subject subject, final int type, final Collection elements)    {      this (subject, type);      for (Iterator it = elements.iterator(); it.hasNext(); )        {          Object o = it.next();          if (type == PRINCIPALS && !(o instanceof Principal))            {              throw new IllegalArgumentException(o+" is not a Principal");            }          if (!elements.contains (o))            {              elements.add (o);            }        }    }