Activiti and ApacheDS integration purpose

Activiti and ApacheDS integration purpose

I'm new in Activiti, and I can't grasp the reason for what to use Activiti
+ ApacheDS
NOTE In Activiti, there's no validation if the user who claims the user
task is also part of the candidate user or group. The Engine doesn't even
validate whether the user is known. This makes it easy to plug in your own
identity management solution, which can, for example, be an LDAP
repository. It's a best practice to define a list of candidate users or
groups and only claim the user task with a user that's on this list. The
validation logic that checks if a user exists in your identity management
system and whether the user is part of a specific group must be
implemented by you.
But I can specify the users & groups for each task by the Activiti
possibilities without ApacheDS. Moreover, after authentification, user
information stores in the application, so I don't need to ask ApacheDS
every time.
My question is:
For what should I use Activity and ApacheDS integration?