String headerToString(){
  String pString=principalsToString();
  if (pString.length() == 0) {
    return codebaseToString();
  }
 else {
    return codebaseToString() + ", " + pString;
  }
}

String headerToString ( ) { String pString = principalsToString ( ) ; if ( pString . length ( ) == 0 ) { return codebaseToString ( ) ; } else { return codebaseToString ( ) + ", " + pString ; } }
convert the header portion , i . e . codebase , signer , principals , of this policy entry into a string
