Alfresco CMIS gets inconsistent results on sort with cmis:lastModifiedBy

Our implementation of Alfresco CMIS gets inconsistent results on a sort with cmis:lastModifiedBy and cmis:createdBy. Hassan Janjua brought this up to me:

"We are violating the spec. CMIS Spec says results must be sorted if order by is used (http://docs.oasis-open.org/cmis/CMIS/v1.1/CMIS-v1.1.html).
I verified this with CMIS Product Management team. We need to create bug JIRA on this."

Steps to Replicate:

Tested this on 5.0 using this query:

. Created folder1 under repository
. Created 3 text files: test1.txt, test2.txt, test3.txt
. Created two users: testuser1 2testuser
. Modified test1.txt with testuser1
. Modified test3.txt with 2testuser

Observed:

. Run the following queries with CMIS workbench:

SELECT cmis:lastModifiedBy FROM cmis:document where in_folder('workspace://SpacesStore/50fd4388-74db-4845-84ed-740f34de5f5c') order by cmis:lastModifiedBy

2testuser
admin
testuser1

SELECT cmis:lastModifiedBy FROM cmis:document where in_tree('workspace://SpacesStore/50fd4388-74db-4845-84ed-740f34de5f5c') order by cmis:lastModifiedBy

admin
admin
2testuser
testuser1
testuser1
2testuser

Expected:

The list with in_tree should be returned as:

2testuser
admin
testuser1