When I execute thenApply method of a CompletableFuture, the execution of this method is happening in the ForkJoinPool thread, not on caller (main) thread. Why is it so? This behavior of using the fork join pool, instead of caller thread, is similar to when using thenApplyAsync, so I want to understand the reason behind this behavior of thenApply

        System.out.println("hello world, CompletableFuturesRightHere");
        System.out.println("log1: " + Thread.currentThread().getName());

        CompletableFuture cf = CompletableFuture.supplyAsync(() -> {
            System.out.println("log-sA: " + Thread.currentThread().getName());
            return 40;
        }).thenApply( a ->  {
            System.out.println("log-tA: " + Thread.currentThread().getName());
            return a + 40;
        });

        System.out.println("log3: " + Thread.currentThread().getName());
        System.out.println("cf result: " + cf.get());

below is output of above code:

hello world, CompletableFuturesRightHere
log1: main
log-sA: ForkJoinPool.commonPool-worker-3
log3: main
log-tA: ForkJoinPool.commonPool-worker-3
cf result: 80

When I run the same code in jdoodle, the behavior is as expected.