Big AD Groups synchronization not working as expected

Steps to reproduce :

• Install LDAP application 9.5.5 and configure it with an AD LDAP directory
• On a groovy page write a script that initializes a org.xwiki.contrib.ldap.XWikiLDAPUtils {{object, the XWikiLDAPUtils }}object will be used to retrieve users of a big AD group, (number of users > 1500), in 2 ways using the  API :

  public Map<String, String> getGroupMembers(String groupDN, XWikiContext context) throws XWikiException

   (https://github.com/xwiki-contrib/ldap/blob/772ad170c09d83e7d8cf6ad8c830414c80ed1a86/ldap-authenticator/src/main/java/org/xwiki/contrib/ldap/XWikiLDAPUtils.java#L820)

• • 1) Call the getGroupMembers(..) method using the group DN
  • 2) Call the getGroupMembers(..) method using a search query (filter) of the same group, something like :  (&(..)(MemberOf=CN=$GROUP_DN))

Expected result : 

The method "getGroupMembers(..)" return all the group members in both cases when the group DN is used and when a filter is used.

Current result :

• The method getGroupMembers(..) return 0 members when the group DN is used
• The method getGroupMembers(..) return all group members (> 2000 users)