Iterable<String> convertValueOf(Iterable<Integer> x) {
  Collection<String> y = new LinkedList<String>();
  for(Integer i : x)
    y.add(String.valueOf(i));
  return y;
}

...
          
Iterable<String> convertForDatabase(Iterable<Integer> x) {
  Collection<String> y = new LinkedList<String>();
  for(Integer i : x)
    y.add(new StringBuilder(i + 7).reverse().toString());
  return y;
}