adhoc view table with two groups and on column

I created a table in an adhoc view of jasperreports server 7.5, with two  groups (column1 and colunm2) and one column (column1)

The sequence of group to be active is firstly column2 and then column1(sql like select column1 from test group by column2,column1) but not  firstly column1 and then column2.

This phenomenon is different from the one of jasperreports server 6.4(sql like select column1 from test group by column1,column2)

I think it is an bug in jasperreports server 7.5. How to fix it?

Thank you!