The problem here is that the char is that it is mapped to CHAR(1) in the database, and not VARCHAR(1) since that, in all cases except this, would be unnecessary. The problem here is that the CHAR type uses whitespace as a padding, and therefore interprets this inserted whitespace as if the CHAR(1) is empty. You can read more here:

http://dev.mysql.com/doc/refman/5.0/en/char.html

or here for a more H2 specific explanation (it works the same way):

http://www.h2database.com/html/datatypes.html#char_type

Unfortunately this is a problem that can only be solved with a workaround or changing the CHAR(1) to VARCHAR(1). This would, in my eyes, not be the way to go for hibernate, but I will investigate this further. You can manually change it to VARCHAR(1) in the database which probably will fix the problem.