I tried to setup in DataGrip an Oracle connection under SYS user.
But got error:
ORA-28009: connection as SYS should be as SYSDBA or SYSOPER
But there is no option in GUI to choose as SYSDBA
option.
Coming back here two years later, it seems to be not possible anymore to change the advanced properties in the connection settings.
Instead you have to supply sys as sysdba
as username.
(This might seem obvious but took me a while to find this out)