OdbcConnection.ServerVersion may return null but docs says it will throw or return "" instead

See docs: https://docs.microsoft.com/en-us/dotnet/api/system.data.odbc.odbcconnection.serverversion?view=dotnet-plat-ext-3.1

but implementation OdbcConnectionOpen.ServerVersion will return null in some cases.

Either docs or implementation should be fixed here.

Found when applying nullable annotations