Without support of MIME charset by i18n API, the application which handles MIME
has to have inconsistent interface to get desired MIME charset to operate.
HJV and HJB has it's own workaround.

ex. the e-mail written in Japanese to send out shalll be encoded as iso-2022-jp and it's actual conversion should be done by CharToByteJIS.

There are no comprehensive methods in i18n API to do that.

It should at least support

Locale.getMIMEcharset()
Locale.getMIMEcharset(Locale target)
Locale.getDefaultMIMEcharset()

and

ByteToChar, CharToByte should recongnize "ISO-2022-xx"