Fix #1736 index request incorrectly doing not resolved

Author: gmarz

src/Nest/CommonAbstractions/Infer/Id/Id.cs

@@ -30,7 +30,7 @@ internal string GetString(IConnectionSettingsValues nestSettings)
 		{
 			if (this.Document != null)
 			{
-				return nestSettings.Inferrer.Id(this.Document);
+				Value = nestSettings.Inferrer.Id(this.Document);
 			}
 
 			var s = Value as string;

src/Nest/Document/Single/Index/IndexRequest.cs

@@ -17,18 +17,20 @@ public partial interface IIndexRequest<TDocument> : IIndexRequest where TDocumen
 	public partial class IndexRequest<TDocument> 
 		where TDocument : class
 	{
-		protected override HttpMethod HttpMethod => ((IIndexRequest<TDocument>)this).Id == null ? HttpMethod.POST : HttpMethod.PUT;
+		protected override HttpMethod HttpMethod => GetHttpMethod(this);
 
 		partial void DocumentFromPath(TDocument doc) => this.Document = doc;
 
 		object IIndexRequest.UntypedDocument => this.Document;
 
 		public TDocument Document { get; set; }
+
+		internal static HttpMethod GetHttpMethod(IIndexRequest<TDocument> r) => (r.Id != null && r.Id.Value != null) ? HttpMethod.PUT : HttpMethod.POST;
 	}
 
 	public partial class IndexDescriptor<TDocument>  where TDocument : class
 	{
-		protected override HttpMethod HttpMethod => Self.Id == null ? HttpMethod.POST : HttpMethod.PUT;
+		protected override HttpMethod HttpMethod => IndexRequest<TDocument>.GetHttpMethod(this);
 		partial void DocumentFromPath(TDocument doc) => Assign(a => a.Document = doc); 
 		object IIndexRequest.UntypedDocument => Self.Document;
 

src/Tests/Document/Single/Index/IndexUrlTests.cs

@@ -22,6 +22,16 @@ await POST("/project/project")
 				}))
 				;
 
+			await POST("/project/project")
+				.Fluent(c => c.Index(new { }, i => i.Index(typeof(Project)).Type(typeof(Project))))
+				.Request(c => c.Index(new IndexRequest<object>("project", "project") { Document = new { } }))
+				.FluentAsync(c => c.IndexAsync(new { }, i => i.Index(typeof(Project)).Type(typeof(Project))))
+				.RequestAsync(c => c.IndexAsync(new IndexRequest<object>(typeof(Project), TypeName.From<Project>())
+                {
+					Document = new { }
+				}))
+				;
+
 			await PUT("/project/project/NEST")
 				.Fluent(c => c.Index(project))
 				.Request(c => c.Index(new IndexRequest<Project>("project", "project", "NEST") { Document = project }))