code: public Node removeUncompletedCorrelationId(String id) {
          NodePlaceholder placeholder=uncompletedCorrelationIdsNodeMap.remove(id);
          if (placeholder != null) {
              return placeholder.getNode();
          }
          return null;
      }
docs: This method removes the uncompleted correlation id and its
  associated information.
  
  @param id The correlation id
  @return The node associated with the correlation id