code: protected void unsetMonitor(ServiceReference<FileMonitor> monitorRef) {
          MonitorHolder holder = fileMonitors.remove(monitorRef);
  
          if (holder != null) {
              holder.destroy();
          }
      }
docs: Remove an instance of a <code>FileMonitor</code> service (provider of
  that interface). Called whenever an instance of this service is removed
  from the service registry.
  
  @param monitorRef
  a reference to the FileMonitor instance to remove