Why is my Spring @Autowired field null?

Another solution would be to put a call of
`SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this)`
to `MileageFeeCalculator` constructor like this:

@Service
public class MileageFeeCalculator {

@Autowired
private MileageRateService rateService; // <--- will be autowired when constructor is called

public MileageFeeCalculator() {
SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this)
}

public float mileageCharge(final int miles) {
return (miles * rateService.ratePerMile());
}
}