> So the client must supply the role in the connection string in order
> to make that role's privileges available to the user (provided the
> user has privileges for that role, natch!)

In JayBird this means that you have to pass "sql_role_name" parameter
in the connection string:

Properties props = new Properties();
props.setProperty("user", "sysdba");
props.setProperty("password", "masterkey");
props.setProperty("sql_role_name", "PRODUCTION");

Connection conn = DriverManager.getConnection(url, props);

Or you can specify it directly in the JDBC URL (see documentation for
examples).

Roman