Empty login AND password combination is not treated as no-authentication mode

[ivanthescientist]

Some DB tools always send empty string in place of Username and Password (instead of nulls). If the cluster operates in no authentication mode, it will throw an exception upon receiving non-null Login/Password, therefore making it impossible to connect to the cluster from a tool that always sends non-null Login/Password.

A workaround for this is to treat empty string in Login AND Password as a no-auth mode and just send nulls instead.