I am trying to use HSQLDB as an embedded database in a spring application (for testing). As the target production database is Oracle, I would like to use HSQLDBs Oracle synt
This option was introduced with HSQLDB 2.0.
Are you sure you are using the correct version?
Maybe you have 1.8 still in the classpath somewhere.
But that won't get you far in terms of testing anyway, because this only turns on some basic syntax "replacing", there is no real behaviour change involved here (and I'm not even talking about more advanced Oracle features like analytical functions, CONNECT BY or something similar).
It is very seldom a good idea to test your application with a DBMS that will not be used in production. It is simply not a valid test.