private Map loadAllServices()

in apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/boot/ServiceManager.java [59:100]
40 lines of code
8 McCabe index (conditional complexity)

    private Map<Class, BootService> loadAllServices() {
        Map<Class, BootService> bootedServices = new LinkedHashMap<>();
        List<BootService> allServices = new LinkedList<>();
        load(allServices);
        for (final BootService bootService : allServices) {
            Class<? extends BootService> bootServiceClass = bootService.getClass();
            boolean isDefaultImplementor = bootServiceClass.isAnnotationPresent(DefaultImplementor.class);
            if (isDefaultImplementor) {
                if (!bootedServices.containsKey(bootServiceClass)) {
                    bootedServices.put(bootServiceClass, bootService);
                } else {
                    //ignore the default service
                }
            } else {
                OverrideImplementor overrideImplementor = bootServiceClass.getAnnotation(OverrideImplementor.class);
                if (overrideImplementor == null) {
                    if (!bootedServices.containsKey(bootServiceClass)) {
                        bootedServices.put(bootServiceClass, bootService);
                    } else {
                        throw new ServiceConflictException("Duplicate service define for :" + bootServiceClass);
                    }
                } else {
                    Class<? extends BootService> targetService = overrideImplementor.value();
                    if (bootedServices.containsKey(targetService)) {
                        boolean presentDefault = bootedServices.get(targetService)
                                                               .getClass()
                                                               .isAnnotationPresent(DefaultImplementor.class);
                        if (presentDefault) {
                            bootedServices.put(targetService, bootService);
                        } else {
                            throw new ServiceConflictException(
                                "Service " + bootServiceClass + " overrides conflict, " + "exist more than one service want to override :" + targetService);
                        }
                    } else {
                        bootedServices.put(targetService, bootService);
                    }
                }
            }

        }
        return bootedServices;
    }