code: public ArrayList<SchemaField> getSchema()
      {
          final ArrayList<SchemaField> items = new ArrayList<SchemaField>(schemaFields.values());
  
          Collections.sort(items, new Comparator<SchemaField>()
          {
              @Override
              public int compare(final SchemaField left, final SchemaField right)
              {
                  return left.getId() - right.getId();
              }
          });
  
          return items;
      }
docs: Get the schema as a collection of fields.
  We guarantee the ordering by field id.
  
  @return the sorted collection of fields