docs: public ComputationGraphUpdater getUpdater(boolean initializeIfAbsent){
          if (solver == null && initializeIfAbsent) {
              solver = new Solver.Builder().configure(conf()).listeners(getListeners()).model(this).build();
              solver.getOptimizer().setUpdaterComputationGraph(new ComputationGraphUpdater(this));
          }
          if(solver != null) {
              return solver.getOptimizer().getComputationGraphUpdater();
          }
          return null;
      }