@CheckReturnValue
    protected final boolean tryEmit(int ordinal, @Nonnull Object item) {
        return outbox.offer(ordinal, item);
    }
@Test
    public void when_tryEmitTo1And2_then_emittedTo1And2() {
        // When
        boolean emitted = p.tryEmit(ORDINALS_1_2, MOCK_ITEM);

        // Then
        assertTrue(emitted);
        validateReceptionAtOrdinals(MOCK_ITEM, ORDINALS_1_2);
    }