// assumes that each set is a singleton or less (as is done for the samples)
      for (Object elem : elements) {
        @SuppressWarnings("unchecked") // safe by generator contract
        Entry<String, Collection<Integer>> entry = (Entry<String, Collection<Integer>>) elem;
        Integer value = Iterables.getOnlyElement(entry.getValue());
        builder.put(entry.getKey(), value);
      }

      // assumes that each set is a singleton or less (as is done for the samples)
      for (Object elem : elements) {
        @SuppressWarnings("unchecked") // safe by generator contract
        Entry<String, Collection<Integer>> entry = (Entry<String, Collection<Integer>>) elem;
        Integer value = Iterables.getOnlyElement(entry.getValue());
        builder.put(entry.getKey(), value);
      }