public List<DocumentImportEntity> ArangoCollection.importDocuments(
        Collection<?> values,
        DocumentImportOptions options,
        int numThreads,
        int batchSize) {

    // Create a fixed thread pool executorService of numThreads
    ExecutorService executorService = Executors.newFixedThreadPool(numThreads);

    // Use Guava or Apache Commons Collections to partition the List
    // Below, I use Apache Commons Collections to partition the original collection of values into smaller sublists
    List<? extends List<?>> batches = ListUtils.partition(new ArrayList<>(values), batchSize);

    List<CompletableFuture<DocumentImportEntity>> completableFutureList = new ArrayList<>();
    for (List<?> batch : batches) {
        CompletableFuture<DocumentImportEntity> completableFuture = CompletableFuture.supplyAsync(() -> {
            DocumentImportEntity documentImportEntity = importDocuments(batch, documentImportOptions);
            return documentImportEntity;
        }, executorService);
        completableFutureList.add(completableFuture);
    }
    List<DocumentImportEntity> documentImportEntityList = new ArrayList<>();
    for (CompletableFuture<DocumentImportEntity> completableFuture : completableFutureList) {
        DocumentImportEntity documentImportEntity = completableFuture.get();
        documentImportEntityList.add(documentImportEntity);
    }
    return documentImportEntityList;
}

DocumentImportOptions documentImportOptions = new DocumentImportOptions()
        .waitForSync(false)
        .onDuplicate(DocumentImportOptions.OnDuplicate.replace)
        .complete(false)
        .details(true);

Collection<MyPojoObjects> values = collection of 10 million objects;
int numThreads = 8;
int batchSize = 1000000; // 1 million

ArangoCollection.importDocuments(values, documentImportOptions, numThreads, batchSize)