Found from investigating CWD-1140 - see my first comment there for more context.

1. Add an LDAP connector (e.g. ApacheDS 1.5)
2. Add a group
3. View the group and set description to " " (i.e. 2 spaces), click update
4. Verify in LDAP directory that group now has a description attribute which is set to 2 spaces
5. View the group and set the description to "Pony", click Update

Observed

Success message but description is still blank in UI. In LDAP, group now has 2 description attributes (" " and "Pony").

Expected

Success message & description changes to Pony in UI. In LDAP, group has 1 description attribute with value of "Pony"