MitreID Connect : Retrieve LDAP operational attributes - attributes

Question

I'm working on the LDAP overlay of MitreID Connect project and everthing is working greatly:
Authentication
Retrieving attributes from LDAP Directory
The problem I have now, is how to retrieve operational attributes in LDAP directory.
I'm not good with Spring development, but I found some documentation which treat this sub, but I'm not able to make it work.
Here's what I found:
Retrieving operational attributes
Ldap Server maintains many operational attributes internally. Example entryUUID is an operational attribute assigns the Universally Unique Identifier (UUID) to the entry. The createTimestamp, modifyTimestamp are also operational attributes assigned to the entry on create or update. These operational attributes does not belong to an object class and hence they were not returned as part of your search or lookup. You need to explicitly request them by their name in your search or build the custom AttributeMapper implementation with matching attribute names.
Now let’s try to retrieve the entryUUID, first you need to build the search controls like this,
SearchControls controls = new SearchControls();
controls.setSearchScope(SearchControls.SUBTREE_SCOPE);
controls.setReturningObjFlag(false);
controls.setReturningAttributes(new String[]{"entryUUID"});
Once you have search control then it’s simply calling search method just like retrieving any other attributes.
ldapTemplate.search("baseName", "(objectclass=person)", controls, new AttributesMapper() {
public Object mapFromAttributes(Attributes attrs) throws NamingException {
Attribute attrUuid = attrs.get("entryUUID");
return attrUuid;
}});
Here is another way to do the same using ContextMapper,
ldapTemplate.search("baseName","(objectclass=person)", 1, new String[]{"entryUUID"},
new ContextMapper(){
public Object mapFromContext(Object ctx) {
DirContextAdapter context = (DirContextAdapter)ctx;
return context.getStringAttributes("entryUUID");
}
});
Let’s add the filter based off of operational attributes like below,
OrFilter orFilter = new OrFilter();
orFilter.or(new GreaterThanOrEqualsFilter("createTimestamp", "YYYYMMDDHHMMSSZ"));
orFilter.or(new LessThanOrEqualsFilter("modifyTimestamp", "YYYYMMDDHHMMSSZ"));
Now call the above search with the filter
ldapTemplate.search("baseName", orFilter.encode(), controls, new AttributesMapper() {
public Object mapFromAttributes(Attributes attrs) throws NamingException {
Attribute attrUuid = attrs.get("entryUUID");
return attrUuid;
}});