code: public ExtendedSwidProcessor setProductId(final String... productIdList) {
          if (productIdList.length > 0) {
              for (String productId : productIdList) {
                  swidTag.getProductId().add(new Token(productId, idGenerator.nextId()));
              }
          }
          return this;
      }
docs: Defines product identifiers (tag: product_id).
  
  @param productIdList
  product identifiers
  @return a reference to this object.