Added Min/MaxChildren to HasChildFilterDescriptor

.. correspondingly as it was implemented in HasChildQueryDescriptor.cs

Author: Jörg Battermann

src/Nest/DSL/Filter/HasChildFilterDescriptor.cs

@@ -13,7 +13,13 @@ public interface IHasChildFilter : IFilter
 		[JsonProperty("type")]
 		TypeNameMarker Type { get; set; }
 
-		[JsonProperty("query")]
+        [JsonProperty("min_children")]
+        int? MinChildren { get; set; }
+
+        [JsonProperty("max_children")]
+        int? MaxChildren { get; set; }
+
+        [JsonProperty("query")]
 		IQueryContainer Query { get; set; }
 
 		[JsonProperty("filter")]
@@ -34,7 +40,9 @@ protected internal override void WrapInContainer(IFilterContainer container)
 		}
 
 		public TypeNameMarker Type { get; set; }
-		public IQueryContainer Query { get; set; }
+        public int? MinChildren { get; set; }
+        public int? MaxChildren { get; set; }
+        public IQueryContainer Query { get; set; }
 		public IFilterContainer Filter { get; set; }
 		public IInnerHits InnerHits { get; set; }
 	}
@@ -57,7 +65,11 @@ bool IFilter.IsConditionless
 
 		TypeNameMarker IHasChildFilter.Type { get; set; }
 
-		IQueryContainer IHasChildFilter.Query { get; set; }
+        int? IHasChildFilter.MinChildren { get; set; }
+
+        int? IHasChildFilter.MaxChildren { get; set; }
+
+        IQueryContainer IHasChildFilter.Query { get; set; }
 
 		IFilterContainer IHasChildFilter.Filter { get; set; }
 
@@ -87,8 +99,20 @@ public HasChildFilterDescriptor<T> Type(string type)
 			Self.Type = type;
 			return this;
 		}
-
-		public HasChildFilterDescriptor<T> InnerHits()
+        
+        public HasChildFilterDescriptor<T> MinChildren(int minChildren)
+        {
+            Self.MinChildren = minChildren;
+            return this;
+        }
+
+        public HasChildFilterDescriptor<T> MaxChildren(int maxChildren)
+        {
+            Self.MaxChildren = maxChildren;
+            return this;
+        }
+
+        public HasChildFilterDescriptor<T> InnerHits()
 		{
 			Self.InnerHits = new InnerHits();
 			return this;