easyadmin bundle sort custom generated columns on sortable field

Question

Have EasyAdmin bundle config like this, and added list fields, and some of them added marked as sortable, some not. And cant find nowhere how to make sortable field: 1) which is relation field from another entity. I.e. OtherEntityName.columnName; 2) which is custom generated field from i.e. 2 fields (here is fullname which is made from firstname and lastname fields from the EntityName entity

easy_admin:
    entities:
        EntityName:
            class: App\Entity\EntityName
            label: EntityName
            list:
                fields:
                    - {property: id, sortable: true}
                    - {property: createdAt, sortable: true}
                    - {property: fullName, sortable: true}
                    - {property: OtherEntityName.columnName, sortable: true}

cant find how to make it sortable, but not sorted by default. Need to make it admin action to sort, not by default like in this example:

easy_admin:
    entities:
        EntityName:
            class: App\Entity\EntityName
            label: EntityName
            list:
                fields:
                    - {property: id, sortable: true}
                    - {property: createdAt, sortable: true}
                    - {property: fullName, sortable: true}
                    - {property: OtherEntityName.columnName, sortable: true}
                sort: ['createdAt', 'ASC']