code: private EsRequest findOrCreateDoc(String nodeKey) throws IOException {
          EsRequest doc = client.getDocument(name(), workspace, nodeKey);
          return doc != null ? doc : new EsRequest();
      }
docs: Searches indexed node's properties by node key or creates new empty list.
  
  @param nodeKey node key being indexed.
  @return list of stored properties as json document or empty document
  if not found.
  @throws IOException