Adding Complicated Selections To Eclipse Link Criteria Builder?

How to add select case

when to_char(trunc(TO_DATE ('03-APR-2015','DD-MM-YYYY'), 'mm'), 'FMDAY') = 'SUNDAY'
then to_number(to_char(TO_DATE ('03-APR-2015','DD-MM-YYYY'), 'W'))+1
             else ceil((to_char(TO_DATE ('03-APR-2015','DD-MM-YYYY'), 'dd') + 1 - to_char(next_day(trunc(TO_DATE ('03-APR-2015','DD-MM-YYYY'), 'mm'), 'SUNDAY'), 'dd'))/7)+1
        end week_no
from dual
query to Eclipse Link CriteriaBuilder

I am able to add distinct(to_char(sum(datecolumn,number),'W-MM-YYYY')) like
 
                       Expression sum = cb.sum(CriteriaQueryUtils.getPath(rt, breakupFields), cb.literal(miliSecToAdd));
                        Expression<String> literal = cb.literal("W-MM-YYYY");
                        Expression<String> functionselectclause = cb.function("TO_CHAR", String.class, sum,literal);
                        return query.select(functionselectclause ).distinct(true).where(p).orderBy(orders);

But need to know how to add case when else to CriteriaBuilder...