code: public Optional<Integer> getInteger(String key) {
          Objects.requireNonNull(key, Required.KEY.toString());
  
          String value = this.values.get(key);
          if (StringUtils.isNotBlank(value) && NumberUtils.isCreatable(value)) {
              return Optional.of(Integer.valueOf(value));
          }
  
          return Optional.empty();
      }
docs: Retrieves an optional integer value corresponding to the name of the form element
  
  @param key The name of the form element
  @return Optional of Integer