Spring Async not executing tasks in parallel

Question

I am trying to execute HTTP requests on a target in parallel using Apache HTTP Client and Spring's async feature.

Here is the Async configuration:

@Configuration
@EnableAsync
public class BackOfficeConfig {
    @Bean(name = "junctionNodeTaskExecutor")
    public Executor junctionNodeTaskExecutor() {
        int nThreads = Runtime.getRuntime().availableProcessors() * 100;
        return new ConcurrentTaskExecutor(Executors.newFixedThreadPool(nThreads));
    }
}

Now in a service, I have the following methods:

@Async("junctionNodeTaskExecutor")  // Async methods have to be public
public void checkJunctionNode(JunctionNode junctionNode) {
    JunctionNodeChecker junctionNodeChecker = new JunctionNodeChecker(junctionNode);
    Instant now = Instant.now();

    // Details dealing with sending the HTTP request
}

private void collectJunctionNodes() {
    logger.info("Inside add Junction Node");
    List<JunctionNode> junctionNodeList = new ArrayList<>();
    int count = 0;
    while (count < 100) {
        JunctionNode junctionNode = (JunctionNode) rabbitMQService.getFromQueue(RabbitMQConfig.QUEUE_CHECK_JUNCTION_NODE);
        if (junctionNode == null)
            break;
        junctionNodeList.add(junctionNode);
        count++;
    }
    logger.info("Collected JunctionNode count: {} for checking", count);
    junctionNodeList.forEach(this::checkJunctionNode);
}

The method collectionJunctionNodes, collect the node objects from a rabbitMQ queue 100 at a time. In the logs I can see the following message:

Collected JunctionNode count: 100 for checking

This is as expected. Now I have 100 nodes but when I send those 100 to be executed in parallel using the forEach stream statement in the line below, I see in the logs of checkJunctionNode that each node is being checked in 5-6 seconds. No parallel execution.

What is going wrong?