Supporting Continuity Camera

To support Continuity Camera I am creating a special NSMenuItem with

item.identifier = NSMenuItem.importFromDeviceIdentifier

When the menu is selected I would suspect the event to trigger Continuity Camera and then provide the data via responder chain to the NSViewController

class MainViewController : NSViewController {

   override func validRequestor(forSendType sendType: NSPasteboard.PasteboardType?, returnType: NSPasteboard.PasteboardType?) -> Any? {

    print("validRequestor")

    if let pasteboardType = returnType, NSImage.imageTypes.contains(pasteboardType.rawValue) {
      return self
    } else {
      return super.validRequestor(forSendType: sendType, returnType: returnType)
    }
  }

But given that this is not triggering anything I am wondering what I might be missing.

Any pointers?