Select with concat function not working in 8.4.1

[Guilherme Nunes]

Greetings.

In upgrading to solr 8.4.1, the following streaming expression is not working 
for me:

select( 
        cartesianProduct(
                tuple(k1="1", k2=array(a)), 
                k2, productSort="k1 asc"), 
        "k1”, 
        concat(fields="k1",delim=",",as="node")  )

Returning “"Invalid expression 
select(cartesianProduct(tuple(k1=1,k2=array(a)),k2,productSort=\”k1 
asc\"),\"k1\",concat(fields=k1,delim=\",\",as=node)) - unknown operands found"”.

But it works fine in 8.2.0.

Am I missing something, or should a jira ticket be opened for this?

Thank you

Kind regards,
Guilherme Nunes