Pass prefix when flattening index settings

A bug that manifests itself if index settings are more than 1 level deep.

Author: russcam

src/Nest/IndexModules/IndexSettings/Settings/IndexSettingsConverter.cs

@@ -95,7 +95,8 @@ public JObject Flatten(JObject original, string prefix = "", JObject newObject =
 			newObject = newObject ?? new JObject();
 			foreach (var property in original.Properties())
 			{
-				if (property.Value is JObject && property.Name != "analysis") Flatten(property.Value.Value<JObject>(), property.Name + ".", newObject);
+				if (property.Value is JObject && property.Name != "analysis")
+					Flatten(property.Value.Value<JObject>(), prefix + property.Name + ".", newObject);
 				else newObject.Add(prefix + property.Name, property.Value);
 			}
 			return newObject;
@@ -214,4 +215,4 @@ private static void Set<T>(IIndexSettings s, IDictionary<string, JProperty> sett
 			settings.Remove(key);
 		}
 	}
-}
+}