Bitbucket com.atlassian.bitbucket.watcher Interface WatcherService unwatch not working

I have a user watching a repository. I wrote a plugin to unwatch any users this repository. The unwatch request returns a false. Not sure if the new UnwatchRequest.Builder(repository) method call is causing a problem because it is suppose to have a Watchable argument which I assume to be repository:

        // impersonate user watching repository
        securityService.impersonating(userService.getUserBySlug(slug),         "deleteWatchers").applyToRequest();

        unwatchRequestBuilder = new UnwatchRequest.Builder(repository);
        unwatchRequest = unwatchRequestBuilder.build();
        if (watcherService.unwatch(unwatchRequest))
        {
            logger.debug("Unwatching repository for user: " + slug + " successful");
        }
        else
        {
            logger.debug("Unwatching repository for user: " + slug + " failed");
        }