code: public void completeConference(String connId, String parentConnId) throws WorkspaceApiException {
          this.completeConference(connId, parentConnId, null, null);
      }
docs: Complete a previously initiated two-step conference identified by the provided IDs. Once completed,
  the two separate calls are brought together so that all three parties are participating in the same call.
  @param connId The connection ID of the consult call (established).
  @param parentConnId The connection ID of the parent call (held).