Can't create a new LDAP connector directory with anonymous bind user dn

Symptoms

When creating a new LDAP connector directory, it's impossible to save the directory without specifying the bind user "User DN" and "Password". Testing the connection with the anonymous credentials works fine.

This will show up as the following error messages in the interface:

1. "The User DN cannot be blank for this directory." under "User DN"
2. "Password cannot be blank." under "Password"

Neither of these fields are marked with an asterisk to indicate that they are mandatory.

Steps to Reproduce

1. Directories > Add Directory
2. Connector
3. Fill in all details, and leave "User DN" and "Password" empty in the "Connector" tab
4. Try to save the directory

Workaround

There are two possible workarounds:

1. Use a username and password instead of anonymous access
2. Use the latest version of Crowd that doesn't have this bug - 2.5.1