public DSet union(DSet otherSet)
    {
        DSetImpl result = new DSetImpl(getPBKey());
        result.addAll(this);
        result.addAll(otherSet);
        return result;
    }
public DSet union ( DSet otherSet ) { DSetImpl result = new DSetImpl ( getPBKey ( ) ) ; result . addAll ( this ) ; result . addAll ( otherSet ) ; return result ; }
Create a new <code>DSet</code> object that is the set union of this
<code>DSet</code> object and the set referenced by <code>otherSet</code>.
@param	otherSet	The other set to be used in the union operation.
@return	A newly created <code>DSet</code> instance that contains the union of the two sets.