code: 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;
              }
          });
      }
docs: Stores a "dataversion" record in the ES store.  There is only a single one of these.  The
  return value of the add will include the version number of the entity.  This version
  number is what we use to determine whether our cache is stale.