docs: public int get(DateTimeFieldType fieldType) {
          if (fieldType == null) {
              throw new IllegalArgumentException("The DateTimeFieldType must not be null");
          }
          if (isSupported(fieldType) == false) {
              throw new IllegalArgumentException("Field '" + fieldType + "' is not supported");
          }
          return fieldType.getField(getChronology()).get(getLocalMillis());
      }