fix: prevent connection overwrite (#275)

---------

Co-authored-by: David Leek <[email protected]>

src/Unleash/Communication/UnleashApiClient.cs

@@ -283,12 +283,13 @@ private static void SetRequestHeaders(HttpRequestMessage requestMessage, Unleash
             requestMessage.Headers.TryAddWithoutValidation(instanceIdHeader, headers.InstanceTag);
             requestMessage.Headers.TryAddWithoutValidation(supportedSpecVersionHeader, headers.SupportedSpecVersion);
 
-            requestMessage.Headers.TryAddWithoutValidation(identifyConnectionHeader, headers.ConnectionId);
             requestMessage.Headers.TryAddWithoutValidation(identifyAppNameHeader, headers.AppName);
             requestMessage.Headers.TryAddWithoutValidation(identifySdkHeader, headers.SdkVersion);
 
             SetCustomHeaders(requestMessage, headers.CustomHttpHeaders);
             SetCustomHeaders(requestMessage, headers.CustomHttpHeaderProvider?.CustomHeaders);
+
+            requestMessage.Headers.TryAddWithoutValidation(identifyConnectionHeader, headers.ConnectionId);
         }
 
         private static void SetCustomHeaders(HttpRequestMessage requestMessage, Dictionary<string, string> headers)

tests/Unleash.Tests/Communication/RequestMessageHeadersTest.cs

@@ -0,0 +1,19 @@
+using NUnit.Framework;
+
+namespace Unleash.Tests.Communication
+{
+    public class RequestMessageHeadersTest
+    {
+        [Test]
+        public void RequestMessageHeaders_Should_Contain_Headers()
+        {
+            var requestMessage = new HttpRequestMessage();
+            requestMessage.Headers.TryAddWithoutValidation("header1", "value1");
+            requestMessage.Headers.TryAddWithoutValidation("header1", "value2");
+
+            Assert.That(requestMessage.Headers.Count, Is.EqualTo(1));
+            Assert.That(requestMessage.Headers.First().Key, Is.EqualTo("header1"));
+            Assert.That(requestMessage.Headers.First().Value.Last(), Is.EqualTo("value2"));
+        }
+    }
+}