removing by
/* the attributes below used in the Preview mode*/
request.getSession().removeAttribute(MAP_QUESTION_CONTENT_LEARNER);
request.getSession().removeAttribute(TOTAL_QUESTION_COUNT);
request.getSession().removeAttribute(CURRENT_QUESTION_INDEX);
request.getSession().removeAttribute(MAP_GENERAL_OPTIONS_CONTENT);
request.getSession().removeAttribute(MAP_OPTIONS_CONTENT);
request.getSession().removeAttribute(QUESTION_LISTING_MODE_COMBINED);
request.getSession().removeAttribute(PREVIEW_ONLY);