I had this exception while testing (junit) my code.
It seems that when you use +Hibernate.org Lob annotation and use HsqlDB, the default column size is probably less than the actual size you are trying to insert. In my case i annotated String with Lob (hibernate knows it should be clob) while my string length was huge -> got this exception.
To fix this, add hibernate column annotation with column length bigger like 15000 , this will solve it (for example of course).
Hoped it helped,