@Override public boolean addEntry(Principal caller,AclEntry entry) throws NotOwnerException {
  if (!isOwner(caller))   throw new NotOwnerException();
  if (entryList.contains(entry))   return false;
  entryList.addElement(entry);
  return true;
}

@ Override public boolean addEntry ( Principal caller , AclEntry entry ) throws NotOwnerException { if ( ! isOwner ( caller ) ) throw new NotOwnerException ( ) ; if ( entryList . contains ( entry ) ) return false ; entryList . addElement ( entry ) ; return true ; }
adds an acl entry to this acl . an entry associates a principal ( e . g . , an individual or a group ) with a set of permissions . each principal can have at most one positive acl entry ( specifying permissions to be granted to the principal ) and one negative acl entry ( specifying permissions to be denied ) . if there is already an acl entry of the same type ( negative or positive ) already in the acl , false is returned .
