code: private static ProductPartitionNode copyCustomParametersToNode(
        BiddableAdGroupCriterion biddableCriterion, ProductPartitionNode node) {
      if (biddableCriterion.getUrlCustomParameters() == null
          || biddableCriterion.getUrlCustomParameters().getParameters() == null) {
        return node;
      }
      for (CustomParameter customParameter :
          biddableCriterion.getUrlCustomParameters().getParameters()) {
        node.putCustomParameter(customParameter.getKey(), customParameter.getValue());
      }
      return node;
    }
docs: Utility method that copies {@link CustomParameter}s
  from a {@link BiddableAdGroupCriterion} to a {@link ProductPartitionNode}.
  
  @param biddableCriterion the source of the copy process.
  @param node the destination of the copy process.
  @return {@code node}.