According to the documentation: "Label values may contain any Unicode characters.", but the doc is missing the fact that the double quote character can't be used inside the label value otherwise it will be impossible to find the end of the string. Seems like those characters must be escaped in order to be properly parsed by prometheus.
|For Gerrit Dashboard: MB-50398|
|168969,2||MB-50398: Escape double quotes in prometheus label values||master||ns_server||Status: MERGED||+2||+1|