return getProjectSelectors(pa -> pa.optional() && pa.active());
    }

    /**
     * @return Required inactive project selectors, never {@code null}.
     */
    public Set<String> getRequiredInactiveProjectSelectors() {
        return getProjectSelectors(pa -> !pa.optional() && !pa.active());
    }

    /**
     * @return Optional inactive project selectors, never {@code null}.
     */

        performProjectActivation(
                parser.parse(options, new String[] {"-pl", "!test1,-test2,-?test3,!?test4"}), activation);
        assertContainsExactlyInAnyOrder(activation.getRequiredInactiveProjectSelectors(), "test1", "test2");
        assertContainsExactlyInAnyOrder(activation.getOptionalInactiveProjectSelectors(), "test3", "test4");

        activation = new ProjectActivation();

        projectActivation.getActivations().stream()
                .filter(pa -> pa.activationSettings().active())
                .forEach(pas -> {});

        Set<String> requiredSelectors = projectActivation.getRequiredInactiveProjectSelectors();
        Set<String> optionalSelectors = projectActivation.getOptionalInactiveProjectSelectors();
        if (!requiredSelectors.isEmpty() || !optionalSelectors.isEmpty()) {