docs: private static MessagePackException unexpected(String expected, byte b)
      {
          MessageFormat format = MessageFormat.valueOf(b);
          if (format == MessageFormat.NEVER_USED) {
              return new MessageNeverUsedFormatException(String.format("Expected %s, but encountered 0xC1 \"NEVER_USED\" byte", expected));
          }
          else {
              String name = format.getValueType().name();
              String typeName = name.substring(0, 1) + name.substring(1).toLowerCase();
              return new MessageTypeException(String.format("Expected %s, but got %s (%02x)", expected, typeName, b));
          }
      }