Problem Statement/Rationale

I created a user on the database admin with role `readWriteAnyDatabase`, and I just wanna connect another database named users by using admin as the authentication database.

But I found that official docs say the path of connection URI is `defaultAuthDb`, but `mongo` command actually use it as the db to connect.

And `mongo --help` says it connects to the database specified by path.

$ mongo --help
MongoDB shell version v5.0.13
usage: mongo [options] [db address] [file names (ending in .js)]
db address can be:
  foo                   foo database on local machine
  192.168.0.5/foo       foo database on 192.168.0.5 machine
  192.168.0.5:9999/foo  foo database on 192.168.0.5 machine on port 9999
  mongodb://192.168.0.5:9999/foo  connection string URI can also be used

Steps to Reproduce{}

1. Authenticated as root user to create a test user on database admin:

use admin
db.createUser({
  name: 'test-user',
  password: passwordPrompt(),
  roles: ['readWriteAnyDatabase'],
})

2. Use the test user to connect to database users, and actual results:

# connected to database admin
$ mongo mongodb://test-user@hidden-info1.mongodb.rds.aliyuncs.com:3717,hidden-info2.mongodb.rds.aliyuncs.com:3717/admin?replicaSet=mgset-62919502

1. authentication failed, it meant mongosh used the URI path, named users, as the authentication database.
   $ mongo mongodb://test-user@hidden-info1.mongodb.rds.aliyuncs.com:3717,hidden-info2.mongodb.rds.aliyuncs.com:3717/users?replicaSet=mgset-62919502

1. connected to database users
   $ mongo mongodb://test-user@hidden-info1.mongodb.rds.aliyuncs.com:3717,hidden-info2.mongodb.rds.aliyuncs.com:3717/users?replicaSet=mgset-62919502 --authenticationDatabase admin
   
   # connected to database users
   $ mongo "mongodb://test-user@hidden-info1.mongodb.rds.aliyuncs.com:3717,hidden-info2.mongodb.rds.aliyuncs.com:3717/users?replicaSet=mgset-62919502&authSoure=admin"

1. connected to a database named test
   $ mongo "mongodb://test-user@hidden-info1.mongodb.rds.aliyuncs.com:3717,hidden-info2.mongodb.rds.aliyuncs.com:3717/?replicaSet=mgset-62919502"
   

   Expected Results

Above examples means that, the db name in path is actually always the connecting target db.

But the official web docs says it's `defaultAuthDb`, and there is nothing about the connecting target db in the docs.

So I expected the docs should say the db name in URI path is always the connecting target db, and then it will be used as default auth db if both `authSource` and `-authenticationDatabase` are unspecified.

Actual Results

Reference the section of Steps To Preproduce.