code: @Override
      public Date getDate(@NonNull String key) {
          if (key == null) { throw new IllegalArgumentException("key cannot be null."); }
  
          return DateUtils.fromJson(getString(key));
      }
docs: Gets a property's value as a Date.
  JSON does not directly support dates, so the actual property value must be a string, which is
  then parsed according to the ISO-8601 date format (the default used in JSON.)
  Returns null if the value doesn't exist, is not a string, or is not parseable as a date.
  NOTE: This is not a generic date parser! It only recognizes the ISO-8601 format, with or
  without milliseconds.
  
  @param key the key
  @return the Date value or null.