code: @Override
      public Object encode(final Mapper mapper, final Object value, final MappedField field) {
          if (isResolved()) {
              Map<String, Object> ids = new LinkedHashMap<String, Object>();
              for (final Entry<String, T> entry : get().entrySet()) {
                  ids.put(entry.getKey(), wrapId(mapper, field, entry.getValue()));
              }
              return ids;
          } else {
              return null;
          }
      }
docs: {@inheritDoc}