Okey, try this:
def getData(){
def returnList = []
List <String>list1 = XYZDomain.executeQuery("select distinct date from XYZDomain")
List <String>list2 = ABCDomain.executeQuery("select distinct Name from ABCDomain")
//iterating list
list1.each {lst->
def map = [:]
map.date = lst
returnList << map
}
//iterating list
list2.each {lst->
def map = [:]
map.name = lst
returnList << map
}
render returnList as JSON
}
That should solve your problem.