@Override
    public @SuppressWarnings("unchecked")
    <T extends Service> T getService(Class<T> serviceType) throws ServiceNotProvidedException {
        Service serviceImpl = services.get(serviceType);
        if (serviceImpl != null) {
            return (T) serviceImpl;
        }

        throw new ServiceNotProvidedException("Service " + serviceType.getName() + " should not be provided, based on moduleDefine define.");
    }
Make sure all required services have been implemented.

@param requiredServices must be implemented by the moduleDefine.
@throws ServiceNotProvidedException when exist unimplemented service.
oap-server/server-library/library-module/src/main/java/org/apache/skywalking/oap/server/library/module/ModuleProvider.java