static <T>T fieldIsPresent(Optional<T> object,String name){
  if (!object.isPresent()) {
    throw new MissingField(name,"must be present");
  }
  return object.get();
}

static < T > T fieldIsPresent ( Optional < T > object , String name ) { if ( ! object . isPresent ( ) ) { throw new MissingField ( name , "must be present" ) ; } return object . get ( ) ; }
check that the given field is present .
