"flat_key","key","int_value","string_value"
"chrome_user_event.action","chrome_user_event.action","[NULL]","action1"
"chrome_user_event.action","chrome_user_event.action","[NULL]","action2"
"chrome_user_event.action_hash","chrome_user_event.action_hash",10,"[NULL]"
"chrome_user_event.action_hash","chrome_user_event.action_hash",20,"[NULL]"
"chrome_user_event.action_hash","chrome_user_event.action_hash",30,"[NULL]"
"event.category","event.category","[NULL]","cat1"
"event.category","event.category","[NULL]","cat2"
"event.category","event.category","[NULL]","cat3"
"event.name","event.name","[NULL]","slice1"
"event.name","event.name","[NULL]","slice2"
"event.name","event.name","[NULL]","slice3"
"is_root_in_scope","is_root_in_scope",1,"[NULL]"
"source","source","[NULL]","descriptor"
"source_id","source_id",12345,"[NULL]"