I created a global variable that contains a list of properties (separate by ",") that I would like to use in the join component.

@a := "";

FOR #i IN 1 .. NumProperties() 
LOOP 
 
@a := @a.",".IthPropertyName(#i);
 
END LOOP;  

@b := substring(@a,2);

Result of the @b is something like this abc*12 9,cde*bf 7,hij*124 (345),lmn*124

4 properties (some properties contains "*" or "(" or ")" ) in the list.

In the Join component, the parameter, "JoinUsing", I put in @b. However, it fail to join the 2 datasets using @b. I have also tried removing all the symbols from the property names but it still would not join using @b. Will appreciate if someone could shed some lights on this question. Thank you!