public static GroupCategorySet union(GroupCategorySet one,GroupCategorySet two){
  Assert.isNotNull(one);
  Assert.isNotNull(two);
  if (one == two)   return one;
  if (one == NONE)   return two;
  if (two == NONE)   return one;
  Set combined=new HashSet();
  combined.addAll(one.asList());
  combined.addAll(two.asList());
  return new GroupCategorySet(combined);
}

public static GroupCategorySet union ( GroupCategorySet one , GroupCategorySet two ) { Assert . isNotNull ( one ) ; Assert . isNotNull ( two ) ; if ( one == two ) return one ; if ( one == NONE ) return two ; if ( two == NONE ) return one ; Set combined = new HashSet ( ) ; combined . addAll ( one . asList ( ) ) ; combined . addAll ( two . asList ( ) ) ; return new GroupCategorySet ( combined ) ; }
creates a new group category set containing the union of the given two group category sets
