Ibatis, Oracle and SelectKey

Another useless waste of 30 minutes, apparently if you're having problems getting Ibatis's selectkey statement to work, in order to get (and return) a generated key, it will fail with something like

com.ibatis.common.jdbc.exception.NestedSQLException:
--- The error occurred in com/x/ods/dao/ibatis/sqlmaps/Entity.xml.
--- The error occurred while applying a parameter map.
--- Check the insertEntity-InlineParameterMap.
--- Check the statement (update failed).
--- Cause: java.sql.SQLException: ORA-01400: cannot insert NULL into
("ODS"."ENTITY_SRC"."ENT_SRC_ID")

the answer? explicitly add the type attribute and set it to "pre". ugh-