How can we maintain insertion order for set when using spring mvc and hibernate with annotation

Question

My requirement is to convert an image to thumbnail, the first image selected by user should get converted to thumbnail, but as of now since i am using set it is not happening. How can i implement this with spring mvc and hibernate. I tried using like the code mentioned below; but it threw error.

Set<UserDefinedClass> object = new LinkedHashSet<UserDefinedClass>

this is done in POJO.