docs: public static XContentBuilder marshall(UserBean bean) throws StorageException {
          try (XContentBuilder builder = XContentFactory.jsonBuilder()) {
              preMarshall(bean);
              builder
                  .startObject()
                      .field("username", bean.getUsername())
                      .field("email", bean.getEmail())
                      .field("fullName", bean.getFullName())
                      .field("joinedOn", bean.getJoinedOn() == null ? null : bean.getJoinedOn().getTime())
                  .endObject();
              postMarshall(bean);
              return builder;
          } catch (IOException e) {
              throw new StorageException(e);
          }
      }