code: @SuppressWarnings("unchecked")
      public T addTag(String tag) {
          if (this.tags_ == null) {
              tags_ = new ArrayList<>();
          }
          this.tags_.add(tag);
          return (T) this;
      }
docs: <p>Adds a tag to the iterable collection of name associated with a deep link.</p>
  
  @param tag {@link String} tags associated with a deep link.
  @return This Builder object to allow for chaining of calls to set methods.