Document.DeleteRelation not removing relation when "outgoing" parameter is "false"

Steps to reproduce

• Install Nuxeo 10.1
• Install Nuxeo API Playground add-on
• Access to Command End points section in your local API Playground: http://localhost:8080/nuxeo/playground/#/commands
• Search "relation"
• Add 2 new relations:

• • Document.AddRelation
    • Input: <FROM document path>, e.g. /default-domain/workspaces/Sample Content/Pictures/Winter.jpg
    • object: <TO document id>, e.g. 29cd982b-fcd4-4679-82db-921cdd737a80
    • predicate: http://purl.org/dc/terms/ConformsTo
    • outgoing: cheked

• • Document.AddRelation
    • Input: <FROM document path>, e.g. /default-domain/workspaces/Sample Content/Pictures/Winter.jpg
    • object: <TO document id>, e.g. 29cd982b-fcd4-4679-82db-921cdd737a80
    • predicate: http://purl.org/dc/terms/ConformsTo
    • outgoing: uncheked

• Both relations are added correctly

• Remove both relations using Document.DeleteRelation end point

• • Document.DeleteRelation
    • Input: <FROM document path>, e.g. /default-domain/workspaces/Sample Content/Pictures/Winter.jpg
    • object: <TO document id>, e.g. 29cd982b-fcd4-4679-82db-921cdd737a80
    • predicate: http://purl.org/dc/terms/ConformsTo
    • outgoing: cheked

• • Document.DeleteRelation
    • Input: <FROM document path>, e.g. /default-domain/workspaces/Sample Content/Pictures/Winter.jpg
    • object: <TO document id>, e.g. 29cd982b-fcd4-4679-82db-921cdd737a80
    • predicate: http://purl.org/dc/terms/ConformsTo
    • outgoing: uncheked

Both operations return a successful result but the second operation doesn't remove the relation.

This operation is NOT removing the relation:

• Document.DeleteRelation
  • Input: <FROM document path>, e.g. /default-domain/workspaces/Sample Content/Pictures/Winter.jpg
  • object: <TO document id>, e.g. 29cd982b-fcd4-4679-82db-921cdd737a80
  • predicate: http://purl.org/dc/terms/ConformsTo
  • outgoing: uncheked

You can check that the relaion has not been deleted using Document.GetLinkedDocuments