Problem Statement/Rationale

The error message in this line is misleading:

https://github.com/mongodb/mongo-tools/blob/460c7e26f65c4ce86a0b99c46a559dccaba3a07d/common/options/options.go#L839 

says:

return ConflictingArgsErrorFormat("authSource", opts.Source, cs.AuthSource, "--authenticationDatabase")

We believe it should be:

return ConflictingArgsErrorFormat("authSource", cs.AuthSource, opts.Source, "-authenticationDatabase")

As this code expects:

https://github.com/mongodb/mongo-tools/blob/460c7e26f65c4ce86a0b99c46a559dccaba3a07d/common/options/options.go#L44 
optionName, uriValue, cliValue, cliOptionName)

Is this something you can fix?