java.lang.reflect.InvocationTargetException in PostConstruct method

I am trying to validate the values returned by a list of methods using java reflection and @PostConstruct spring annotation as it is depicted in the following code snippet :

@Serivce("appConfigService")
public class AppConfigServiceImpl implements AppConfigService{       

    //rest of source code including constructor and other methods is omitted 

    @Override
    public String getServerURL(){//example of a method I am invoking in the postConstruct phase
       //method body omitted
    }

    @PostConstruct
    public void postConstruct() {
        try {
            Class<AppConfigServiceImpl> classObject = AppConfigServiceImpl.class;
            AppConfigServiceImpl appConfigServiceImpl = classObject.newInstance();
            Method[] methods = classObject.getMethods();
            for(Method method: methods)     
                method.invoke(appConfigServiceImpl);            
        } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | InstantiationException e) {
            e.printStackTrace();
        }
    }
}

However when spring executes the postConstruct() method a java.lang.reflect.InvocationTargetException is thrown. I could not figure out the source of the exception. Any help will be more than welcome.