Ldap group membership not updated without a restart

steps to reproduce

1. Integrate bamboo with LDAP
2. Configure the ldap caching so that the cache got refreshed every 20s for example
3. Now create a group and associate a user to it
4. The group will be created and the user associated as expected
5. Now remove the user from the group and wait for the cache to run

Expected behaviour
Bamboo should remove the user from the group as well

Current behaviour
The user is still associated to the group and only a restart will remove the group association from the user. This only affects group membership as user details and creation of new groups get updated immediately. It appears this properties " LDAPGroupManagerReadOnly..groups_hasMembership and LDAPGroupManagerReadOnly..groups_getGroupsForUser" are ignored by the cache.

There is no error in the logs even when the "com.atlassian.user" class is set to DEBUG