Use regexp.QuoteMeta to escape destination when having "+" in front of it

engine/storage_mongo_stordb.go

@@ -1033,13 +1033,10 @@ func (ms *MongoStorage) GetCDRs(qryFltr *utils.CDRsFilter, remove bool) ([]*CDR,
 			if len(prefix) == 0 {
 				continue
 			}
-			if strings.HasPrefix(prefix, "+") {
-				prefix = "\\" + prefix
-			}
 			if len(regexpRule) != 0 {
 				regexpRule += "|"
 			}
-			regexpRule += "^(" + prefix + ")"
+			regexpRule += "^(" + regexp.QuoteMeta(prefix) + ")"
 		}
 		if _, hasIt := filters["$and"]; !hasIt {
 			filters["$and"] = make([]bson.M, 0)