cluster.routing.allocation.exclude metrics are not exposed

[alinix-alinix]

Hello! For some reasons cluster.routing.allocation.exclude._ip is not exposed with exporter, version 1.8.
It exposes watermarks though.

$ > curl -u user:pass -XGET http://localhost:9200/_cluster/settings?pretty | grep -C 10 allocation
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   600  100   600    0     0   264k      0 --:--:-- --:--:-- --:--:--  585k
{
  "persistent" : {
    "cluster" : {
      "routing" : {
        "allocation" : {
          "disk" : {
            "watermark" : {
              "low" : "0.85",
              "flood_stage" : "0.95",
              "high" : "0.9"
            }
          },
          "exclude" : {
            "_ip" : "10.178.3.100"
          }
--
      "info" : {
        "update" : {
          "interval" : "1m"
        }
      }
    }
  },
  "transient" : {
    "cluster" : {
      "routing" : {
        "allocation" : {
          "exclude" : {
            "_ip" : ""
          }
        }
      }
    }
  }
}

[alinix-alinix]

well it would be great if we could have 1 or 0 value if setting is set or not.