Ensuring we dont set content, when there is no content - otherwise e.g. GET/HEAD would fail. Setting application/json in ctor now.

Author: Per Kops

src/Atc.Rest.Client/Builder/MessageRequestBuilder.cs

@@ -15,7 +15,7 @@ internal class MessageRequestBuilder : IMessageRequestBuilder
         private readonly Dictionary<string, string> pathMapper;
         private readonly Dictionary<string, string> headerMapper;
         private readonly Dictionary<string, string> queryMapper;
-        private string content = string.Empty;
+        private string? content;
 
         public MessageRequestBuilder(string pathTemplate, IContractSerializer serializer)
         {
@@ -24,6 +24,7 @@ public MessageRequestBuilder(string pathTemplate, IContractSerializer serializer
             pathMapper = new Dictionary<string, string>(StringComparer.Ordinal);
             headerMapper = new Dictionary<string, string>(StringComparer.Ordinal);
             queryMapper = new Dictionary<string, string>(StringComparer.Ordinal);
+            WithHeaderParameter("accept", "application/json");
         }
 
         public HttpRequestMessage Build(HttpMethod method)
@@ -37,10 +38,14 @@ public HttpRequestMessage Build(HttpMethod method)
             }
 
             message.RequestUri = BuildRequestUri();
-            message.Content = new StringContent(content);
-            message.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json");
             message.Method = method;
 
+            if (content is not null)
+            {
+                message.Content = new StringContent(content);
+                message.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json");
+            }
+
             return message;
         }
 
@@ -126,4 +131,4 @@ private Uri BuildRequestUri()
             return new Uri(urlBuilder.ToString(), UriKind.RelativeOrAbsolute);
         }
     }
-}
+}