// From ExecutorService's JavaDoc
private static void shutdownAndAwaitTermination(final ExecutorService pool) {
    pool.shutdown(); // Disable new tasks from being submitted
    try {
        // Wait a while for existing tasks to terminate
        if (!pool.awaitTermination(5, TimeUnit.SECONDS)) {
            pool.shutdownNow(); // Cancel currently executing tasks
            // Wait a while for tasks to respond to being cancelled
            if (!pool.awaitTermination(5, TimeUnit.SECONDS))
                System.err.println("pool did not terminate");
    } catch (InterruptedException ie) {
        // (Re-)Cancel if current thread also interrupted
        // Preserve interrupt status

Consider using LOG::error instead of System.err::println.

Where LOG is:

private static final org.slf4j.Logger LOG = org.slf4j.LoggerFactory.getLogger(CurrentClass.class);