6785456 : Read Kerberos setting from Windows environment variables
We have to create krb5.ini on Windows to show what Kerberos realm and KDC should be used. In fact, on Windows, if the logon user is already a Windows AD account, two environment variables -- USERDNSDOMAIN, LOGONSERVER -- are created by the system for these 2 properties. We should use them when krb5.ini is missing.
These environment variables have been set since Windows 2000.