docs: protected void updateDataVersion() {
          DataVersionBean dv = new DataVersionBean();
          dv.setUpdatedOn(System.currentTimeMillis());
          Index index = new Index.Builder(dv).refresh(false)
                  .index(getDefaultIndexName())
                  .type("dataVersion").id("instance").build(); //$NON-NLS-1$ //$NON-NLS-2$
          getClient().executeAsync(index, new JestResultHandler<JestResult>() {
              @Override
              public void completed(JestResult result) {
                  dataVersion = null;
              }
              @Override
              public void failed(Exception e) {
                  dataVersion = null;
              }
          });
      }