code: public static ProductType createType(ProductDimensionType productDimensionType,
        @Nullable String productTypeValue) {
      Preconditions.checkNotNull(productDimensionType,
          "ProductDimensionType is required when creating a ProductType");
      ProductType productType = new ProductType();
      productType.setType(productDimensionType);
      productType.setValue(productTypeValue);
      return productType;
    }
docs: Creates a new ProductType.
  
  @param productDimensionType required
  @param productTypeValue may be null if creating an "other" dimension