MongoDB连接的时候，能否增加一个用户认证库的参数

MongoDB连接的时候，有的时候，用户的认证库和用户实际存放数据的库不在一起，
例如，有的用户认证库是admin，然后实际存放数据是在test库下，
能否增加一个参数，类似authdb，这个参数是指定用户的认证库的库名。

No files or tests are named in the issue. Start by locating the MongoDB connection configuration and existing authentication options in the Java readers and writers; verify how the target data database is selected. Done means a connection can specify a separate authentication database, such as admin, while continuing to access data in the requested database.

Written by the indexing model from the issue text.