Rest api: unable to unpublish node

I'm trying to unpublish a file from the repository using rest api.
I checked that the FileNode.getUrl method returns correct url to node (see attached file: ResearchController.removeNode) and the node exists.
I also checked that local file (which I pass to the unpublish method) is created.

Using method ResearchController.createNode I can create a node, but I can't remove any one.