The documentation says that the H2 database does not support cross joins:
H2 does support cross join since a long time (I don't remember what version). See: http://www.h2database.com/html/grammar.html#table_expression (CROSS). A condition is not required for cross join.
I think the documentation should be changed, and probably the H2Dictionary should be changed as well (crossJoinClause = "CROSS JOIN"; requiresConditionForCrossJoin = false.