Why number of Threads never exceed the corePoolSize to reach the defined Max?

Question

I'm struggling with the ThreadPoolExecutor settings and don't understand why the number of created threads doesn't reach the defined maximumPoolSize and stay limited to the corePoolSize.

Here are the ThreadPool settings :

public class Parallel {

    public static ThreadPoolExecutor EXECUTOR;

    static {
        ThreadPoolExecutor executorService = new ThreadPoolExecutor(5, Integer.MAX_VALUE, 1,
                TimeUnit.MINUTES, new LinkedBlockingQueue<>());
        executorService.allowsCoreThreadTimeOut();
        EXECUTOR = executorService;
    }

}

When I launch the app, I inject 7 callable tasks and expect the logs to show me that 7 threads have been created. But what I can observe is that only 5 threads have been created when 7 should be in order to parallelize all the submitted tasks.

2021-10-03 15:41:34.034 INFO  [pool-1-thread-2] Task - Thread [ pool-1-thread-2 ] doing things inside Task's call() method
2021-10-03 15:41:34.034 INFO  [pool-1-thread-4] Report - Thread [ pool-1-thread-4 ] doing things inside Report's call() method
2021-10-03 15:41:34.034 INFO  [pool-1-thread-1] Monitor - Launching [ Task | Task(number=4) ] callable
2021-10-03 15:41:34.034 INFO  [pool-1-thread-5] Task - Thread [ pool-1-thread-5 ] doing things inside Task's call() method
2021-10-03 15:41:34.034 INFO  [pool-1-thread-3] Report - Thread [ pool-1-thread-3 ] doing things inside Report's call() method
2021-10-03 15:41:34.034 INFO  [pool-1-thread-1] SuperWrapper - All callables launched
2021-10-03 15:41:34.034 INFO  [pool-1-thread-1] Task - Thread [ pool-1-thread-1 ] doing things inside Task's call() method
2021-10-03 15:41:39.039 INFO  [main] LimitWorkaround - Computing callables...
2021-10-03 15:41:44.044 INFO  [main] LimitWorkaround - Computing callables...

If I change the corePoolSize from 5 to 10, and the maximumPoolSize up to 20 (for example), the logs will show some [pool-1-thread-10] but never more than 10, which is the corePoolSize.

Is there any reason for that ?

Thanx by advance.