code: public void addTemplateId(String id, Integer index) throws HelloSignException {
          List<String> currentList = getList(String.class, TEMPLATE_IDS);
          if (index == null) {
              index = currentList.size();
          } else if (index < 0) {
              throw new HelloSignException("index cannot be negative");
          } else if (index > currentList.size()) {
              throw new HelloSignException("index is greater than template ID list size: " + currentList.size());
          }
          if (index == currentList.size()) {
              add(TEMPLATE_IDS, id); // Just append the item
          } else {
              // Insert the item at the given index
              clearList(TEMPLATE_IDS);
              int limit = currentList.size(); // We'll be adding one
              for (int i = 0; i < limit + 1; i++) {
                  if (i == index) {
                      add(TEMPLATE_IDS, id);
                  }
                  if (i < limit) {
                      add(TEMPLATE_IDS, currentList.get(i));
                  }
              }
          }
      }
docs: Add the template ID to be used at the specified index.
  
  @param id String
  @param index Integer
  @throws HelloSignException thrown if therer is a problem adding the given
  template ID.