formatDate groups not supported

[mstevan]

@mstevan
test-set: format-date.xml
test-cases: format-date-030, format-date-031

@team
Seems that groups are not supported. Please investigate

Input:
format-date(date("2012-05-18"), "[Y9,999,*]") -

Output:
⚠️ ️️here was an error.
 
Code: [RBST0002] (this code can be looked up in the documentation and specifications).
 
Location information: file:/Users/mstevan/Documents/:LINE:1:COLUMN:0:
 
"[Y9,999,*]": groups not supported

Expected output:
2,012