Execute native SQL statements

Hi , 

How to execute the following statements in Cayenne. Trying to access Oracle schema using different account having select permission. 

SET ROLE browse_japan;
ALTER SESSION SET CURRENT_SCHEMA = JAPAN;

Regards,
basu


Note in JDBC I can execute the following it works
. 
Connection connection = dataSource.getConnection();
connection.createStatement().execute("SET ROLE browse_japan");
connection.createStatement().execute("ALTER SESSION SET CURRENT_SCHEMA = JAPAN");