docs: @Override
      public Pair<Gradient, Double> gradientAndScore() {
          if (!logGradient) {
              OneTimeLogger.info(log,
                              "Gradients for the frozen layer are not set and will therefore will not be updated.Warning will be issued only once per instance");
              logGradient = true;
          }
          return new Pair<>(zeroGradient, underlying.score());
      }