Disable multiple partition by clauses in the same sql query

0: jdbc:drill:schema=dfs> explain plan for  select sum(a2) over(partition by a2 order by a2), count(*) over(partition by a2,b2,c2)  from t2 order by 1,2; 
+------+------+
| text | json |
+------+------+
| 00-00    Screen
00-01      Project(EXPR$0=[$0], EXPR$1=[$1])
00-02        SelectionVectorRemover
00-03          Sort(sort0=[$0], sort1=[$1], dir0=[ASC], dir1=[ASC])
00-04            Project(EXPR$0=[CASE(>($3, 0), CAST($4):ANY, null)], EXPR$1=[$5])
00-05              Window(window#0=[window(partition {0, 1, 2} order by [] range between UNBOUNDED PRECEDING and UNBOUNDED FOLLOWING aggs [COUNT()])])
00-06                SelectionVectorRemover
00-07                  Sort(sort0=[$0], sort1=[$1], sort2=[$2], dir0=[ASC], dir1=[ASC], dir2=[ASC])
00-08                    Window(window#0=[window(partition {0} order by [0] range between UNBOUNDED PRECEDING and CURRENT ROW aggs [COUNT($0), $SUM0($0)])])
00-09                      SelectionVectorRemover
00-10                        Sort(sort0=[$0], sort1=[$0], dir0=[ASC], dir1=[ASC])
00-11                          Project(a2=[$1], b2=[$0], c2=[$2])
00-12                            Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=maprfs:///drill/testdata/aggregation/t2]], selectionRoot=/drill/testdata/aggregation/t2, numFiles=1, columns=[`a2`, `b2`, `c2`]]])