Directory synchronisation fails when the name of a group changes in case

From JRA-27353

Steps to reproduce:

1. install JIRA
2. setup LDAP directory - create test data (see below)
3. add LDAP directory in JIRA configuration with option "Enable Nested Groups" enabled
4. synchronize data
5. change name of "sub_group" to "Sub_group" and update uniqueMember parameter of parent_group to match changed name
6. synchronize data again - here crowd should fail on inserting data into database (CWD_MEMBERSHIP table)

I was able to reproduce it with HSQL and PostgreSQL.

Test data - two groups with relation:

parent_group, uniqueMember=

sub_group

LDIF export of my test data (I've configured LDAP to use root entity dc=atlassian,dc=pl):
parent_group.ldif

version: 1

dn: cn=parent_group,dc=atlassian,dc=pl
objectClass: groupOfUniqueNames
cn: parent_group
uniqueMember: cn=sub_group,dc=atlassian,dc=pl
description: Parent group

sub_group.ldif

version: 1

dn: cn=sub_group,dc=atlassian,dc=pl
objectClass: groupOfUniqueNames
cn: sub_group
uniqueMember:
description: Child group

Also to see effect of exception which you should get in step 6 you may add user and set membership using uniqueMember attribute - this user won't be added to any group because of synchronization fail (user should be created, groups also, but no user membership in group will be created).

This can also be reproduced without the use of nested groups.