src/main/java/org/jboss/util/collection/ListSet.java
public boolean add(final Object obj) {
      boolean added = false;

      if (!list.contains(obj)) {
         added = list.add(obj);
      }

      return added;
   }
public boolean add(final Object obj) {
      boolean added = false;

      if (!list.contains(obj)) {
         added = list.add(obj);
      }

      return added;
   }
Add an element to the set.

@param obj  Element to add to the set.
@return     True if the element was added.