New Rewrite Rule for Set of Collections

Found that a new query that collection rule will need to support. Collections in this form are not being found by the rewrite rules to alter the query for parallel processing. The rewriter needs to find all collections and union the result from the new data source scan operators.

Example Query:
for $x in (collection("folder1"), collection("folder2"))
return $x

Search Operators (example section):
unnest $$6 <- function-call: vxquery:

{urn}iterate, Args:[%0->$$5] – |UNPARTITIONED|
assign [$$5] <- [function-call: vxquery:{urn}

concatenate, Args:[%0->$$2, %0->$$4]] – |UNPARTITIONED|
assign [$$4] <- [function-call: vxquery:

{xpath-functions}collection, Args:[function-call: vxquery:{operators-ext}promote, Args:[function-call: vxquery:{xpath-functions}

data, Args:[%0->$$3],

{XMLSchema}int QUANT_ONE(bytes[5] = [1d00000007])]]] – |UNPARTITIONED|
assign [$$3] <- [{XMLSchema}

string QUANT_ONE(bytes[68] = [...])] – |UNPARTITIONED|
assign [$$2] <- [function-call: vxquery:

{xpath-functions}collection, Args:[function-call: vxquery:{urn}promote, Args:[function-call: vxquery:{xpath-functions}

data, Args:[%0->$$1],

{XMLSchema}int QUANT_ONE(bytes[5] = [1d00000007])]]] – |UNPARTITIONED|
assign [$$1] <- [{XMLSchema}

string QUANT_ONE(bytes[66] = [...])] – |UNPARTITIONED|

Suggested new Plan
union all
data source scan (folder1)
data source scan (folder2)