Constructor initialization for collections in termvector response objects

Author: gmarz

src/Nest/Domain/Responses/MultiTermVectorResponse.cs

@@ -17,6 +17,7 @@ public class MultiTermVectorResponse : BaseResponse, IMultiTermVectorResponse
         public MultiTermVectorResponse()
         {
             IsValid = true;
+            Documents = new List<TermVectorResponse>();
         }
 
         [JsonProperty("docs")]

src/Nest/Domain/Responses/TermVectorResponse.cs

@@ -18,6 +18,7 @@ public class TermVectorResponse : BaseResponse, ITermVectorResponse
         public TermVectorResponse()
         {
             IsValid = true;
+            TermVectors = new Dictionary<string, TermVector>();
         }
 
         [JsonProperty("found")]

src/Nest/Domain/TermVector/TermVector.cs

@@ -9,6 +9,11 @@ namespace Nest
     [JsonObject]
     public class TermVector
     {
+        public TermVector()
+        {
+            Terms = new Dictionary<string, TermVectorTerm>();
+        }
+
         [JsonProperty("field_statistics")]
         public FieldStatistics FieldStatistics { get; internal set; }
 

src/Nest/Domain/TermVector/TermVectorTerm.cs

@@ -9,6 +9,11 @@ namespace Nest
     [JsonObject]
     public class TermVectorTerm
     {
+        public TermVectorTerm()
+        {
+            Tokens = new List<Token>();
+        }
+
         [JsonProperty("doc_freq")]
         public int DocumentFrequency { get; internal set; }