@Override
    public boolean tryYield() {
        Optional<Mail> optionalMail = mailbox.tryTake(priority);
        if (optionalMail.isPresent()) {
            try {
                optionalMail.get().run();
            } catch (Exception ex) {
                throw WrappingRuntimeException.wrapIfNecessary(ex);
            }
            return true;
        } else {
            return false;
        }
    }
@Test
    void testTryYield() throws Exception {
        final TestRunnable testRunnable = new TestRunnable();
        CompletableFuture.runAsync(
                        () -> mailboxExecutor.execute(testRunnable, "testRunnable"),
                        otherThreadExecutor)
                .get();
        assertThat(mailboxExecutor.tryYield()).isTrue();
        assertThat(mailboxExecutor.tryYield()).isFalse();
        assertThat(testRunnable.wasExecutedBy()).isEqualTo(Thread.currentThread());
    }