Capgemini Interview Question

what is immutable class. how to write a immutable class with 2 string field and one array list. ? Spring-- how to inject bean? can we inject null? can we have private constructor in bean? is bean thread safe? bean containers and its implementation ? ApplicationContext is interface or class ? what is implementation of ApplicationContext ? @Around advice in spring AOP what design pattern spring framework using apart from MVC, Factory. SpringBoot-- difference b/w @Controller and @RestController Jquery