private static <T> CompletableFuture<T> failedFuture(Throwable ex) {
        CompletableFuture<T> future = new CompletableFuture<>();
        future.completeExceptionally(ex);
        return future;
    }
Utility methods for saving users, groups and tracks.
common/src/main/java/me/lucko/luckperms/common/command/utils/StorageAssistant.java